O'Quinn has long been a reliable character actor, playing recurring roles as authority figures on such shows as The West Wing, Millennium, JAG, Harsh Realm, and Alias, the J.J. Abrams-created series that led to O'Quinn's casting on Lost as island philosopher king John Locke. On film, his most memorable role has been the title character in the underrated 1987 thriller The Stepfather (shown). O'Quinn is alternatingly sympathetic and chilling as a serial killer who marries into ready-made families, then inevitably slaughters the new wife and kids when they fail to measure up to his rigid idea of family values. That ability to seem both fatherly and mysteriously menacing has served O'Quinn well on Lost.