U.S. comedian and actress Sarah Silverman is dating Welsh actor Michael Sheen, UsMagazine.com reported Wednesday. "They were making out at Soho House," the website quoted an unidentified witness as saying about the couple's recent date in Los Angeles. "They were all over each other for a lot of the night." Silverman, 43, was also at Sheen's side at his 45th birthday party in West Hollywood last weekend. The report did not say when the romance began. Silverman previously dated talk-show host Jimmy Kimmel, while Sheen's former girlfriends include English ballet dancer Lorraine Stewart, British film star Kate Beckinsale and Canadian actress Rachel McAdams.