He’s a rock star, he was in the band The Grass Roots in the 1960s. The mention it in the finale, him and the real Creed share almost the same backstory. He’s said in interviews that the character he played on the show was him if he had stayed in The Grass Roots and continued to heavily use LSD and other drugs.

Fun fact: the song he sings during Benihana Christmas is a song by The Grass Roots (https://open.spotify.com/track/5w20jHQZGultaPMtjI5SC0?si=h6hRI-QlRKi2LTBMoHkH4w). His real name is also William Charles Schneider which is referenced in the show (I believe it’s the bankruptcy episode and Creed is explaining that he just transfers all his debt to William Charles Schneider which is him in real life).

If there’s one character I would ever want to meet in real life, it’s him. Jamming with him or playing a show would be a dream come true.