Grogar is a tyrannical, and violent Ram, and main antagonist of Season 8. He is the leader of his own personal army, with numerous different species following under him.
Physical Appearance
Grogar is a large ram, standing taller than an average pony, but has the face resembling more of a goblin. He has large, sharp teeth jutting out of his bottom jaw, and red eyes with no pupils or irises. He has large curved horns and cloven hooves. Around his neck is a golden bell from his rule in Tambalon, though he does sometimes wear a scarfed medallion to show superiority on occasion.
Later on in My Little Universe II, he had his horn cracked off thanks to his fight with Stevonnie. He then lost both of his horns at the end of "The Reef".
In the finale, he gains a "god form" from gaining Discord and White Diamond's magic. He grew a lot taller, gaining a Lion's mane and tail, and gained golden armor for his horns and around his chest. All of these were lost once he is removed of both powers.
Personality
Grogar is a cruel, tyrannical, and brutal leader. He is very malicious in his approach to most subjects, often using violence and brutality to solve most of his problems rather than truly thinking anything through. He's notable for his temper, quickly lashing out at anyone that angers him, and he won't hesitate to kill anyone if it means to either solve a problem, or better gain his goal. This is further expanded on in My Little Universe II, which Steven learned that it doesn't matter to Grogar if he kills someone or not, as he was so used to seeing death everywhere he went.
Despite his tyrannical appearance, he still does hold a sense of morality towards other "less fortunate" races, or creatures that are considered outcasts by others. This trait is shown numerous times, such as him willing to release the Aliens captured by The Diamond Authority, and when he first discovered the Gems harvested into walls for Diamond City's main palace, him almost immediately deciding to gather all harvested Gems and taking them away. His morality though doesn't apply to everyone. In the face of Dragons, he considers them far too dangerous and horrific to even face, to the point when he even gave up in taking over Canterlot at a point simply because Spike was present there, and any attacks on it would be pointless to do. This also shows up with Lion, him still calling Lion as "another stupid animal". He also has a strong belief in traditional monarchy rank, believing that figures that are considered queens and kings truly are the rightful rulers, and others like Twilight Sparkle, and Celestia, just manipulated the world to believe they are in charge without the queen title. The only ruler he thought was actually in charge of Equestria during his reign was Sombra - the only Unicorn with the king title.
History
While not too much is known of his past, Padparadscha vaguely revealed that his past home within Peshtihorn was attacked by a Dragon, a figure named Fawn seemingly involved in rescuing him from the disaster. This is further expanded upon in My Little Universe II in "The Reef", which it's revealed that he was sent off by Fawn to find the Alicorns.
In "Once Upon an End" it is revealed that Celestia, Luna, and Starswirl refused to help him, and as such he lost everything. After that, he spent years becoming stronger and fighting every monster he came across until he confronted them again years later. Thanks to this encounter however, he got sent to Tartarus, and he swore revenge on them all once he could get out.
Season 8
White Diamond Arc
Grogar appears within Canterlot, alongside Bray and Budgerite, overhearing the news about Celestia's death. This news intrigues Grogar, him insisting that with her out of the way they will have Equestria to themselves in little to no time at all, him believing that the alicorns never had true power as they are "princesses" and not true "queens". When Twilight Sparkle left for the Convocation of Creatures, he tries to invade the Canterlot castle, fighting Starlight Glimmer in the process. However, he quickly withdraws once he caught sight of Spike, fearing of an adult Dragon might be somewhere in Canterlot. This alone convinced him that Canterlot could not be taken, not with such a creature around. Shortly after this though, he is informed by Stubby of the Aliens captured by the Diamond Authority, and after hearing of the Harvested Gems decides to take over Homeworld instead.
He doesn't make a full frontal attack at first, taking the time to gather up the Harvested Gems from the Diamond Palace and organizing his army together. At a point however, he is informed of their return after the Era 3 Festival began, and as such decides to go into the diamond Palace himself to retrieve one more Harvested Gem in the form of a statue. He enforced Stubby in distracting the Diamonds with a altered Body Puzzler, him coming out with Bray once they all left. While trying to get the final piece though, he was found by Pink Pearl and Lion, whom of which he nearly shatters Pink Pearl and locks them out of Blue Diamond's bath. When the guard came in sometime later, he quickly confronted them all and defeats them all fairly easily, soon using Pink Pearl as a hostage for the rest of them to stop fighting him. However, Blue Pearl managed to force him to let go, him stating just before leaving that he will kill them all, referring to Blue Pearl as a "Harpy Witch".
Grogar Arc
His true attack onto everyone finally happened shortly afterwards, quickly taking the throne for himself by defeating all Diamonds, and corrupting much of their royal court after Steven refused to join him, claiming it was "his decision". During it all, he managed to capture Connie Maheswaran, semi-corrupting her in the process much to Steven's anger. He reappears sometime later near the Crystal Temple, forcing Steven outside of the Beach House. He proceeded to mock him further by pointing out how he left Pink Pearl behind on Homeworld, how easily he can "break his character", and how he won't stop since Steven won't kill him. In the end, he hits Steven unconscious and leaves him with a temporary scar on his face. During his reign, renaming the city to Tambalon, he decides to take Connie in as his future bride, stating that a king needs a queen, and that a empire is made over generations rather than just one lifetime. He left Connie to think it over for a while. Grogar also appeared when Star Quartz and Padparadscha arrived in Tambalon, telling them that if he chose between life or death and war or peace, he chose War and Death. He orders the others to execute them, but upon hearing Padparadscha talk about his old home, he quickly demands everyone to leave excluding Star and Padparadscha, and tries to get the full story, only to get nothing. Angered, he tries killing them himself, proving unsuccessful.
Since this, he amped up security, and when Flint and Amethyst arrive to "join" his army, he was there to watch it himself to be sure no tricks were played. After hearing some news from Nichrome about more soldiers getting lost, he assigns them to Tempest Shadow to be trained, and went back to preparing for the upcoming wedding. During preparations he was confronted by Connie, and offered a deal to let Twilight Sparkle live. He immediately refused, saying he wasn't a ram who makes deals, and she either had to be his bride or live as an example, mattering little to him which she chose.
The wedding eventually started, but he was confronted by Steven just before the vows could be met. In their conversation, he was challenged to a duel for Homeworld, to which he gleefully accepts and instructs the army to move out. He proceeds to fight Stevonnie up in the docking station of Homeworld, fighting long and hard until Stevonnie ultimately "killed" him with his own broken horn. He however presented two gemstones that seemingly belonged to Garnet, saying how it must suck to be a hero before surrendering.
My Little Universe II
Grogar's cracked horn.
Not long after the battle, it is revealed that Grogar survived the fight he had with Stevonnie, keeping Ruby and Sapphire on him as a necklace as he managed to slip out of Homeworld undetected. He arrived to Earth with intentions on taking over it, gaining the aid of Spinel in order to have her destroy the Harmony Gems for him. When he discovers her intentions to destroy Earth to do so, he quickly turned on her and fought her, as he wanted to take over the world and not destroy it. He quickly changes his mind, telling her he only was using her and that it would never work between them anyway, though he does admit she could've worked well for a captain if she only had better loyalty. Before he had a chance to kill Spinel, he was stopped upon Stevonnie's return, though he at first found it amusing and expected to go into another bloodshed fight with her, only to find that Stevonnie wasn't going to do that and that she didn't have to in order to drive him away. He attempts to scare her, and officially started fighting her when learning that she will not be scared of him anymore. During the fight, he lost Ruby and Sapphire, finding out upon Sunstonnie that Garnet was still alive, much to his shock. By that point, out of rage, he attacked Spinel and Sunstonnie with the Rejuvenator, no longer caring for ruling Earth. As a final resort, he tells Steven that the Gems (and by extension Steven and Twilight Sparkle) will out-live everyone around them, and questions them what they're gonna do after that happens. However, the Gem Injector collapses, and Grogar almost died from it before Steven actually saved his life, to which he questions as he didn't decide not to kill him yet. In the end though, while still refusing Steven's forgiveness, allowed him to keep Beach City and all of his "toys", withdrawing from the battle himself.
From there, he took a break from attacking the Harmony Gems despite technically being at a huge advantage, his reason mainly being that Spinel will kill him if he tried just charging in again. During this break he lost the Storm King, and replaces him for Tempest Shadow and promoted her as a new captain. He eventually returned to fighting again, targeting Steven and Spinel once they isolated themselves in Pink Diamond's Garden, his main target being Spinel as by that point Steven was no longer a danger to him. However, Spinel forcefully made him withdraw, him vowing that she will suffer for it before he left.
He reappears in the two-part special "Snowfall Stars", which he overheard of Steven's plans to celebrate Hearth's Warming in Canterlot, finding it the perfect time to strike it while they were all distracted with the holiday, his plan being to overthrow the remaining Alicorns alongside the weakened White Diamond, taking over Homeworld and Equestria in one go. He made sure his troops followed his plans by reminding them about the Storm King's defeat, getting everyone to prepare for the assault. He arrived inside Canterlot to check on Stubby, Sumu, Budgerite and Bray on their plans only to discover that The Dazzlings found them out. Thanks to Adagio Dazzle however, Grogar decided to form an alliance with them, sending them to help his troops with the upcoming play to unnerve Steven, and later on to lure him into his trap. His plan failed however when the Wyvern suddenly arrived, making him suddenly turn and try to run out of Canterlot. On his way out the Wyvern found him and captured him, taking him and Steven back to his lair. After being dropped off, he refused to leave despite being able to just make a portal to go, mostly thanks to the Wyvern trapping him there though when Steven woke up and questioned him, he tried to play it off as him not wanting Steven to get away. As they waited, Steven tried to tell him he didn't have to be a tyrannical ruler, only for him to say he'd die if he chose anything else, and shows his lack of empathy towards the healing Gems, asking who would care about their state, and making it clear that he will not obey Steven even after he saved his life. This escalated into a potential fight, but Grogar ultimately had to let Steven help him get away from the Wyvern when he tried to eat them. After escaping, Grogar left Steven again.
After the incident, Grogar, driven close to mad thanks to this confusion, placed Tempest Shadow temporarily in charge of the Tambalon Army as he went out to find Steven and get some answers. He eventually found him at Mount Aris, demanding that he explain his previous encounter with Red Diamond and wanting to know how he was still alive, saying it was impossible to see Red Diamond and live. He was willing to kill everyone else in order to make him talk. After Steven reveals everything, Grogar literally laughed at him, finding it so ironic and even exclaimed at Red Diamond to come down and kill him herself, and to give up on her "Pearl". When he saw that Steven and Connie were going to fuse again, he desperately charged in and became apart of the fusion himself, not only creating the Monster Fusion, but also exposing his past to them all. Despite this, he still tried to get them to quit caring about him, and tried to attack them but only knocking himself out.
He later wakes up within the Barn House, and finding Steven there waiting for him alongside Star, Padparadscha, Spinel and Lapis Lazuli. He almost immediately tried to attack them, but finds that he was locked inside a magical barrier to keep him from escaping. He compliments them on how it was actually smart of them to do that, and asks them what they plan to do with him although they can't kill him given he was already dead. Learning that they want to teach him to appreciate life again, he only goes along with them as he felt sorry for them. Throughout the time though, he constantly refuses many of their attempts to change his mind, including driving off the local flower aliens on the Blue Star Moon, ruining Pinkie Pie's welcome back party for Jasper, and driving away Starlight and Trixie when they try to relate to him. He snaps when he got involved with the rest of the Harmony Gems, and beats up Steven severely for his attempts, making it clear that he will never listen to him and that he has never beaten him on his own. He remains locked away by that night, where he was found by Jasper. During their interaction, he reveals to her how he left his army behind, and learns how much he and Jasper actually have in common. He remains within the Barn for a while longer, but while he was there, he had Sumu report his whereabouts to the rest of his army, allowing them rest of his troops to come and break him out. Upon being freed, he sent an all out assault on the Gems for humiliating him, but ultimately fails again, forced to flee.
Grogar's final form after gaining Discord and White Diamond's magic.
After driving Nichrome's troops out of his own army, he stays away from the Harmony Gems for a while, hungry for revenge on how much humiliation they've done to him. During this, he finds out from Sumu about the groups' involvement with the Spirit Council, and he ultimately works out of a plan to finally become powerful enough to stand against them. In the end his plan ultimately works and he gains the powers from both White Diamond and Discord, turning himself into a "god".
During the three-part finale, he goes out on a rampage throughout Equestria, single-handedly taking over Canterlot first and taking the princesses and Starswirl the Bearded hostage. He also takes the time to invade and destroy Ramicorn for the people there giving the Harmony Gems more information about him. When he learns about the location of the Harmony Gems, he gathers up his army to fight them in Sniper's Realm, he himself refusing to fight them as he only wanted to fight the main Gems and Ponies responsible for his humiliation. During the invasion he faces Blue Diamond and Yellow Diamond, both of which he quickly shatters for standing in his way. In the end though he abandons the battlefield, along with Tempest Shadow and her platoon, going out to Homeworld to confront the remaining Harmony Gems himself. In their fight, he is proven too strong for them, and kills them all with the exception being Steven. He tries one more time to convince Steven to join him, telling him how mother nature hates hybrids like them and will do everything to make them suffer. In the end, he defeats Steven, believing to have killed him, and goes back to his army waiting for him. He gloats on about his victory, but discovers the Gems and Ponies he thought he killed alive again. Angry, he orders his army to shoot them and destroy them, but overtime finds them over-powering his army. He joins in the fight later on and tries killing them himself. However, the Harmony Gems then shoot him with his own weapon, the blow draining him of all his magic and launching him out of Homeworld onto Earth through his own portal. He wakes up in Empire City's beach, and when he was confronted by the Harmony Gems and their friends, he reveals that he had a final backup plan, in the form of a corrupted Sumu. They try to force him to change her back, but Grogar reveals that he can't without his magic, and he will take the world with him if he is to get killed, getting swallowed by Sumu shortly afterwards.
When inside of Sumu's core, Steven, Connie, and Spinel find Grogar is still alive, and refuses to let them by him unless they kill him, Grogar trying to make sure the world does die whether they want it or not and demanding satisfaction. During the fight, He manages to tear out Steven's gemstone, and to make sure Steven's dead brutally pummels him afterwards. When Pink Steven appears though, Grogar confronts him, but becomes horrified at the raw power Pink Steven possessed. Even so, he still tries to fight him off, but gets both his horns destroyed and thrown out of Sumu's body for doing so. They find him again back on the beach, and Grogar tries one final time to corrupt them by asking again how they feel about being alone without their friends. In the end after hearing the answer, he finally gives up, saying he can't keep this up anymore and the worlds all belong to them. Red Diamond appears afterwards, and takes Grogar away, the old Ram passing away.
Abilities
Magic
Grogar does hold a strong level of magic, most of which is summoned by his curved horns similar to how Unicorns use their magic. The exact level of magic isn't specified, but is enough to easily topple the royal guard of Canterlot with ease, and destroy The Diamond Authority in one strike. Most of his spells seem to be offensive-based, and used in combat or punishment, amplified with the ringing of his Bell.
As part of his magic, he can also teleport in between worlds by cutting open a portal with his hooves, which is strong enough to travel between Earth, Equus, and Homeworld with ease.