The Night Owl
The Night Owl, is a one-time character who showed up in the episode "The Night Owl" of The Regular Show. He appears as a young man with brown hair and colored sunglasses, and is the owner of his own radio station. In the episode, the Night Owl holds a contest over the radio waves, offering a vintage muscle car for the last person standing on top of a huge billboard. Once he learns that the remaining contestants Mordecai, Rigby, Muscle Man, and High-Five Ghost, have planned to share the car together, he freezes them in liquid nitrogen after fooling them into fighting each other in order to preserve his popularity for eternity.
By the year 4224 AD, the Night Owl is monumentally famous and has a museum which was built around the contest and having his head and mind preserved in an owl-shaped robotic body Once Mordecai and the gang are unfrozen, they take the muscle car to the time machine exhibit that the Night Owl built in his own museum, only to be stopped by the Night Owl himself. The gang, however, ran his robot over which made his head fall out and took the time machine to the very first day of the contest, stopping the Night Owl's contest for good.
The Night Owl from the future later returns in the half-hour special "Exit 9B" as Garrett Bobby Ferguson Jr.'s minions with a non-speaking role.