<P> G. Callen ( born : Grisha Alekandrovich Nikolaev ) is a fictional character in the show NCIS : Los Angeles portrayed by Chris O'Donnell . He is an NCIS Special Agent in Charge , and the senior agent assigned to the Office of Special Projects . O'Donnell made his first appearance during NCIS ' sixth season episode `` Legend ( Part 1 ) '' . </P>
what does g stand for in ncis los angeles
Grisha