Sandy Cohen and Ryan Atwood! Peter Gallagher shared an adorable picture of himself alongside his former O.C. costar Benjamin McKenzie via Twitter in September 2013. "Hey look who I ran into at @kathryng's show the other night! @ben_mckenzie! How great! I love both those kids!" the Covert Affairsactor wrote.The O.C. ended after four seasons in 2007.