Flash

Flash is the so-called fastest sloth working in DMV (Department of Mammal Vehicles) in Zootopia.

Background
Not much is currently known about Flash's background, but as revealed in the second Zootopia trailer he befriended Nick Wilde sometime prior to the events of the film. He is shown to have a liking for jokes, which Nick appears to enjoy to use to his advantage to annoy other animals. At some point prior to Zootopia, Flash got employed at the Department for Mammal Vehicles which is his current occupation.

Trivia

 * His actor Raymond S. Persi previously voiced Gene and Zombie from Wreck-It Ralph, and the Horn from Get a Horse!.
 * It is implied by Nick that Flash got his name due to the fact that he Drag Races for a hobby, a fact which is proven by the end of the movie in which his pulled over by Judy and Nick.