Life on the set of Happy Days wasn't always as cheerful as it appeared on screen, according to Henry Winkler. Henry Winkler has revealed one actor who annoyed him on the set of 'Happy Days' (Getty)Denis Mandel (center) appeared in 10 episodes of 'Happy Days' as Eugene Belvin (Disney General Entertainment Con)While not naming the actor, Winkler then revealed: "He played Eugene." The character was played by actor Denis Mandel, who went on to act in shows including Knots Landing and Homefront before stepping away from acting entirely. Winkler said that, after one particularly frustrating moment on set, Howard offered him a crucial piece of advice: learn to control his temper. "I said, 'Ron, I will never hit my script as long as I live,'" Winkler said.