From Nookipedia, the Animal Crossing wiki
Booker (おまわりさんB, Omawarisan B, Policeman B, もんばんさんB, Monban-san B, Mr. Gatekeeper B) is a bulldog who has appeared in all of the Animal Crossing series games, along with his working partner, Copper. His name refers to "booking" someone meaning to arrest them. He appears nervous and unsure of himself when talking to the player, hesitating to speak using words like "Um..." which contrasts with Copper's personality and bravery. He works (with Copper) twenty-four hours a day, seven days a week taking no breaks, unlike other service characters in the game.
In Animal Crossing, Doubutsu no Mori e+ and Animal Crossing: New Leaf, he wears typical police officer attire; blue police uniform, police cap and badge. In Animal Crossing: Wild World and Animal Crossing: City Folk, he wears typical guardsman attire; red uniform with a white cross on the front and a green helmet. He holds a wooden pike which he pokes the ground with when approached. Other than this, he has the appearance of a typical bulldog, such as the chubby cheeks and the lazy, tired looking eyes.
In Animal Crossing and Doubutsu no Mori e+, Booker is a police officer running the lost and found inside the Police Station. He gives away any of the lost and found items, without question the player on whether they lost that item or not. He appears to question this to himself, by saying "Umm, okay, that's a lot of items," but never acts upon it.
In Animal Crossing: Wild World, Booker stands on the left of the gate inside the Town Gate. He will show the player the lost and found, tell them which visitors are in town (if any) and change the flag to a different design. Like in the original Animal Crossing, he will give away any of the lost and found items away, without questioning the player. The player can also ask "Where am I?" but he will just say "Huh? Oh, no... Honestly, I'm not too sure, but what do you need to know about?" But the player can instead ask Copper for a proper answer.
Aside from slightly different speech, Booker's role in City Folk is exactly the same as in Wild World. He can be found in the same area, inside the town gate on the left hand side. Booker is very shy, and unsure in letting the player change things (like the town flag) and letting the player look inside the Lost and Found. He is also unsure of the exact time that people come through the town gate.
In Animal Crossing: New Leaf, Booker oversees the lost and found within the Police Station, and he will tell the player of any special visitors who are in the town if asked. However, Booker will only appear if the player chooses to construct the Classic Police Station as a public works project. If the Modern Police Station is built as a public works project, Copper will instead maintain the town's lost property service.
Happy Home Designer amiibo Card
When the player is visiting Booker's RV at the campground, the bottom screen will display the following:
Booker, along with Copper, has a chance of appearing as a background character in Smashville, a stage exclusive to the Wii U version. In the 3DS version, he appears alongside with Copper in a trophy.
Names in other languages