From Wikipedia, the free encyclopedia. Peter Killian Gallagher (born August 19, 1955 height 5 10 (1,78 m)) is an American actor, musician and writer. Since 1980, Gallagher has played many roles in numerous Hollywood films. He starred as Sandy Cohen in the television drama series The O.C. from 2003 to 2007. He currently appears in a recurring role on the USA Network drama Covert Affairs as CIA Clandestine Services Director Arthur Campbell. Description above from the Wikipedia article Peter Gallagher, licensed under CC-BY-SA, full list of contributors on Wikipedia.