LOS ANGELES (Hollywood Reporter) - Ari Gold has a friend. Who knew?

Gary Cole is set to join HBO's comedy "Entourage" as a regular next season, playing Hollywood agent Andrew Klein, Ari's (Jeremy Piven) oldest Hollywood friend from their early days in the business.

Cole is introducing the character this season in a three-episode arc slated to air in November.

"Entourage," which is halfway though its fifth season, recently was picked up for a sixth season to begin production in early 2009 for a summer launch.

Cole recently co-starred in the Judd Apatow-produced "Pineapple Express" and on ABC's "Desperate Housewives." In November will join the cast of the Steppenwolf Theater Company production of "August: Osage County" at London's National Theater.

TVBurnout/Reuters/Hollywood Reporter