Hi Five Ghost, sometimes unofficially spelled as High-Five Ghost, and nicknamed Hi Fives, Five, HFG, or even just Fives by Muscle Man, is one of the main characters of Regular Show. Hi Five Ghost is a ghost who works alongside Mordecai and Rigby as a groundskeeper at The Park, as well as the best friend of Muscle Man. Hi Five Ghost made his first debut as a cameo character in the Pilot. He then made his official appearance in The Power.