Mark Greene

Mark Greene, M.D. is a fictional character from the American medical drama series ''ER''. Portrayed by actor Anthony Edwards, he first appeared in the series' pilot episode, as well as subsequently appearing as one of the principal characters until the end of the eighth season. Edwards later returned to make a guest appearance in the fifteenth season episode "Heal Thyself".

Considered to be the lead protagonist of the series’ first eight seasons, Greene's role was that of a mediator and occasional authority figure. He begins the series as the ER's chief resident, before being promoted to an attending physician. He became the only member of the original set of main characters who died during the series. Provided by Wikipedia