Big Shot : Noun. An important or influential person. Mischa Barton's rep has confirmed that the former "O.C." actress recently was approached for an upcoming role on "Gossip Girl" but turned it down. When are these network execs gonna get it? Mischa Barton is too much of a big shot for your little "television shows." She was on "The O.C." for like, three years. I think the girl's paid her ...