​From Wikipedia, the free encyclopedia. Michael O'Neill (born May 29, 1951) is an American actor. With a career stretching through three decades, he usually portrays senior law enforcement or military officers. He is perhaps best known for his role as Special agent Ron Butterfield, the head of President Josiah Bartlet's Secret Service detail, on The West Wing. He played CTU Administrative Director Richard Walsh in the first two episodes of 24. He played Sgt. Maj. Ron Cheals in the CBS action-drama series The Unit. He starred in the Season Six 2 part Finale of Grey's Anatomy as the broken widower who holds the hospital hostage with a 9mm while pursuing the doctors responsible for unplugging his wife. His most notable film performances occur in Seabiscuit, Secondhand Lions, Transformers, Dancer, Texas Pop 81, Traffic, Sea of Love, A Quiet Little Marriage, Nothing But the Truth, and Green Zone. O'Neill graduated from Auburn University in 1974. After attending Auburn he spent time under the tutelage of actor Will Geer and his daughter, Ellen, at Theatricum Botanicum in Los Angeles before moving to New York to pursue his career there. Michael O'Neill(1947년생, Montgomery, Alabama, USA) 는 배우로, 대표작으로 달라스 바이어스 클럽, ATF, Cold Call가 있으며, 그 외에도 멘탈리스트, 그레이 아나토미, NCIS, 크리미널 마인드, 스와트, CSI: 마이애미, 우주전쟁, 프리즌 브레이크, 24, 웨스트 윙, 엑스 파일, NCIS: 로스앤젤레스 등 다양한 작품에 출연했다. (오뜨랑에서 실시간으로 번역된 한글 프로필도 확인할 수 있어요) 2025년 우주전쟁에서 Secretary of Defense Walter Crystal 역을 맡았다. 2025년 브라이드 하드에서 Frank 역을 맡았다. 2025년 해피 페이스에서 D.A. Craig Calloway 역을 맡았다.