Mark

Gordon Katsumoto (91 episodes)

Dr. Ken (Room 731)

Ivan Hess (4 episodes)

School Superintendent

Mike Serrano (1 episode)

Tom Chang (1 episode)

Steve Kim (1 episode)

Private Young

Oscar (3 episodes)

Dr. Ken

Adam (1 episode)

Dr. Lyle

Agent Wang

Kimball Cho (151 episodes)

En-Joo

Chaplain Alan Lantz (2 episodes)

Koh (1 episode)

Mr. Brenneman (1 episode)

Warren Chen (1 episode)

Liam Kelly (1 episode)

Agent Alec Wong

Detective Kent Yoshihara (5 episodes)

Murakami (1 episode)

Young John

Paul the Attorney

Dr. Harrison Wong (1 episode)