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Tom Selleck as Thomas Sullivan Magnum IV: Magnum character’s back-story includes a previous career as a former U.S. Navy SEAL. He’s a third generation naval officer, the son of a deceased naval aviator killed during the Korean War. He is also a 1967 graduate of the United States Naval Academy and Vietnam veteran, where he served as a Sea-Air-Land Force (SEAL) commando.
Magnum’s specialized training includes acquiring appropriate expertise as a counter-insurgency expert, and also demonstrating additional expertise in lock picking and safe-cracking.
Magnum played the field position of quarterback for the United States Naval Academy football team. The Magnum character is depicted to have resigned his commission in the U.S. Navy in disillusionment after approximately eleven years of service, including three tours of service during the U.S. military involvement in the Vietnam War. Magnum takes his Private Investigator job quite seriously and does not appreciate abbreviations for his profession such as P.I. and private eye — whenever referred to in such a manner he corrects the person and remarks that he is a “private investigator.” It is also not clear what his age or place of birth is. In the season-two episode “Try To Remember,” Magnum reports his date of birth (to an examining doctor) as August 8, 1944, his place of birth as Virginia, and his mother’s name as Martha. These answers seem to satisfy the doctor (who, of course, has access to Magnum’s medical records), though Magnum had sustained an injury to the head following a car accident. In the scene, his head is bandaged, and he has difficulty remembering the accident. The date of birth conflicts with inferences from at least two other episodes. Tom Selleck’s mother’s name is, in fact, Martha.
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Roger E. Mosley as Theodore “T.C.” Calvin: a helicopter pilot who operates a tourist charter business called Island Hoppers, wherein he pilots a Hughes 500D helicopter, decked out with distinctive livery. A former Marine Corps helicopter pilot in Vietnam, T.C.’s combat-trained flight skills are often
solicited and put to good use by Magnum during the course of an investigation. T.C. is also powerfully built, a trait which Magnum often benefits from when he expects to, and often does, run into physical trouble. With the exception of some early season 1 episodes, T.C. avoids alcohol, instead preferring milk, soda, or juice, but mostly coffee.
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Larry Manetti as Orville Wilbur Richard “Rick” Wright: a suave playboy who is manager of the King Kamehameha Club, an exclusive beachfront members-only club. In the pilot, Rick owned Rick’s Cafe Americaine (a.k.a. “The Snow Palace”). Rick also maintains a number of underworld contacts (one of whom is Francis “Icepick” Hofstetler, played by Elisha Cook Jr., a loan shark, gang boss, and Rick’s stepfather), and is an expert in weaponry…he was T.C.’s door gunner during the war in Vietnam.
- John Hillerman as Jonathan Quayle Higgins III:

