In addition to Bogart, Lazar became the agent representing other celebrities, including Lauren Bacall, Truman Capote, Cher, Joan Collins, Noël Coward, Ira Gershwin, Cary Grant, Moss Hart, Ernest Hemingway, Gene Kelly, Madonna, Walter Matthau, Larry McMurtry, Vladimir Nabokov, Clifford Odets, Cole Porter, William Saroyan, Irwin Shaw, President Richard Nixon and Tennessee Williams. Lazar's power became such that he could negotiate a deal for someone who was not even his client and then collect a fee from that person's agent. Oscar Levant said of Lazar, "Everybody who matters has two agents: his own and Irving Lazar."