Geggis Pek was a renowned musician who performed in the Crimson Casino on the space station gambling resort the Wheel at some point prior to the Battle of Yavin, during the tenure of Simon Greyshade as the station's administrator.
Sources
Viva Space Vegas! The History of the Marvelous Wheel: Part 1 on StarWars.com (original link is obsolete) (First mentioned)
Viva Space Vegas! The History of the Marvelous Wheel: Part 2 on StarWars.com (original link is obsolete)