William Joseph Devane (born September 5, 1939) is an American film,  television and theatre actor, perhaps best known for his role as Greg Sumner on the primetime soap opera Knots Landing (1983–1993) and as James Heller on the serial drama 24 (2005–2007, 2014). He is also known for his supporting roles in films such as McCabe & Mrs. Miller (1971), Marathon Man (1976), and Space Cowboys (2000).