What is the name of the nonexistent secret agent in 'North by Northwest'?

The nonexistent secret agent in Alfred Hitchcock’s North by Northwest is George Kaplan.

Kaplan is an invented identity created by a U.S. intelligence agency as a decoy. Enemy agents are led to believe Kaplan is a real operative, making him useful for diverting attention from the agency’s actual plans and agents.

Advertising executive Roger Thornhill is mistakenly identified as Kaplan after a hotel page summons that name. The misunderstanding drives the film’s central chase: Thornhill is kidnapped, framed for murder, pursued across the country and forced to investigate an identity that does not belong to anyone.

A common mix-up is choosing Roger Thornhill or Eve Kendall. Thornhill, played by Cary Grant, is the innocent man caught in the deception, while Kendall is a genuine intelligence agent working undercover. The 1959 film’s government-secrets microfilm is the MacGuffin behind the espionage plot.