EXCLUSIVE: There is nothing that infuriates Hollywood agencies more than when they feel they haven’t had warning that a client is about to leave. Which is why CAA’s Bryan Lourd et al asked for a “save” meeting for this morning with Robin Williams. (And CAA is expert at keeping clients with these “save” meetings, I should add.) However, people in the Academy Award-winning actor’s camp tell me that he did give them sufficient warning and therefore turned down CAA’s request. So it’s now official: WME’s Adam Venit and Marc Geiger have signed Williams in all areas. And Lourd is livid. This is not the first time that Williams has left CAA under unpleasant circumstances. He was the first CAA client to leave the agency and join Michael Ovitz’s ill-fated management company. That sparked a war between Ovitz and the partners of the agency he co-founded like Lourd. After Ovitz’s AMG failed, CAA accepted Williams back into the fold.

Williams, who besides his Supporting Actor Oscar for Good Will Hunting also has 2 Emmys and 5 Grammys, will next be heard in Happy Feet 2 and seen in The Big Wedding opposite Robert De Niro and Diane Keaton. Last spring, Williams received great reviews for his Broadway debut in Bengal Tiger At The Baghdad Zoo. But for an agency like WME, Williams’ continuing career as a stand-up comedian is what’s really lucrative: His most recent tour, “Robin Williams: Weapons of Self-Destruction,” was one of 2010’s most successful, grossing $40 million, as well as becoming the subject of an HBO special and comedy album nominated for a Grammy.