After the series' cancellation in 1971, Selby played Quentin Collins in Night of Dark Shadows, the second feature film based on the show, released later the same year.

He continued to appear in a number of film and television roles during the 1970s, including U-Turn (1973), The Super Cops (1974) and Rich Kids (1979), and episodes of The Waltons (1974), Police Woman (1975), and Kojak (1976).

Selby was nominated for a Golden Raspberry Award for Worst Supporting Actor for his role in the 1980 film Raise the Titanic, which was met with a negative reception from critics and audiences along with poor box-office takings.

Originally considered an antagonist, Richard gradually became more of a protagonist, and by the final season, he was the central character of the show (in part due to the health-related absence of Wyman).

Selby continued in numerous film and TV roles during the 1990s and 2000s, including Dying Young (1991), White Squall (1996) and Surviving Christmas (2004), and episodes of series such as Cold Case (2007) and Mad Men (2009).