Officer Dick is the playable police officer who appears as an unlockable original character in Tony Hawk's Pro Skater.
Unlike the game's professional skateboarders, Officer Dick was created specifically for the series rather than being a real-life skater. He is presented as a comic secret character: a uniformed police officer who can be selected after being unlocked. His exaggerated identity fits the game's irreverent tone and its willingness to mix authentic skating with jokes and fictional personalities.
Officer Dick is not the only unlockable original character in the first game. Private Carrera is the other major original unlockable, but she is not a police officer. That makes Officer Dick the single best answer among the listed choices. Ollie the Bum is also associated with the wider Tony Hawk character roster, but the name in this question refers to a different character and does not describe the playable police officer.
The original game otherwise centers on ten real professional skaters, including Tony Hawk, Bob Burnquist, Kareem Campbell, and Elissa Steamer. Its secret characters helped establish the series' tradition of humorous unlockables and guest appearances.