By The Book is a middle-aged Unicorn Pony in charge of the police department for Fillydelphia.
Personality
By The Book is shown to be more level-headed due to his experience as an officer, willing to allow Steven Universe's help in the case, and calling Hard Case out on blaming Spike for little reason. He believes everything should be documented to help ponies remember how to deal with any crisis if the same one happens again.
History
Season 7
By The Book appeared on the scene after one of the buildings on Fillydelphia was set on fire by an unknown assailant, him specifically keeping the crowds back for their own safety. When he figured out it was Steven Universe witnessing the event, he had him and his friends return to the station for questioning as they've helped aid Equestria numerous times prior. He agrees to let them help in the situation despite Hard Case's annoyance, bringing them out for a stakeout that night, and with their help managed to drive off the creature causing the fires within the city.