Scott Vincent Baio (; born September 22, 1960) is an American actor. He is known for playing Chachi Arcola on the sitcom Happy Days (1977–1984) and its spin-off Joanie Loves Chachi (1982–1983), the title character on the sitcom Charles in Charge (1984–1990), Dr. Jack Stewart in the medical-mystery-drama series Diagnosis: Murder (1993–1995), and the title role of the musical film Bugsy Malone (1976), his onscreen debut. Baio has guest-starred on various television programs, appeared in several independent films, and starred on the Nickelodeon sitcom See Dad Run (2012–2014).