Old Gregg is portrayed by Noel Fielding. He was created for "The Legend of Old Gregg", a 2005 episode of the TV series. He later went on to appear in the 2006 stage show, The Mighty Boosh
Old Gregg is a hermaphroditic merman who occasionally refers to his vagina, which emits a blinding light, as his "mangina." He inhabits a cave below the lake in a village called Black Lake. Old Gregg is fond of Bailey's Irish Cream, as well as being a watercolour painter. He owns The Funk, an extraterrestrial covered in 'udder-like' teats which lactate liquid funk. Old Gregg is in love with Howard Moon; singing a song with him entitled "Love Games", chronicling his obsession and Howard's reluctance, and later proposing to Howard. A deleted scene from "The Legend of Old Gregg" documents many rumours about Old Gregg, including his cannibalistic nature, and his age at over 1,200 years old. Before meeting Faye, Old Gregg was obsessed with Slash, the former Guns N' Roses guitarist, to the point of kidnapping him. It was mentioned that it ended badly, involving Gregg being very upset and Slash plummeting from a helicopter down 1000 feet onto some sharp rocks. He also claims that he said, "You should build a Velvet Revolver and go and live in it." - Velvet Revolver being Slash's new band.
Old Gregg is first seen in the 2005 episode, "The Legend of Old Gregg" in which he meets and falls in love with Howard, who is then rescued by Vince. Old Gregg then joins Howard in the 2006 stage show, after tracking him down and having himself delivered in a box, where they sing a rendition of "Love Games" and are later seen kissing. Old Gregg last appeared in deleted scene from the 2007 episode, "Party", disguised as a woman who has taken a liking to Howard. The episode became popular on YouTube and Old Gregg became something of an internet meme.
There is a legend of an Old Gregg merman that existed at Orford Castle in Suffolk. The tale is that this merman was caught in fishermen's nets in about 1167 and was held for six months until he escaped. The creature was naked, covered in hair and never talked.