The daughter of Austrian Jewish immigrants, Martel was billed as "Arline Sax" during the early years of her television career. One of her earliest appearances was in the December 25, 1959 Twilight Zone episode "What You Need" as a girl in the bar (speaking role). She appeared in a 1960 episode of The Rebel entitled "The Hunted" in which she had a scene with Leonard Nimoy, prior to Star Trek. She was also featured in two 1961 episodes of Route 66: "Legacy for Lucia", in which she had the title role of a Sicilian girl who inherits an American soldier's estate, and "The Newborn", in which she played a mother who dies in childbirth.
In 1962, Martel made her first of two appearances on Perry Mason, as Fiona Cregan in "The Case of the Absent Artist". Later, she guest starred as Sandra Dunkel in "The Case of the Dead Ringer" (1966) when Raymond Burr played a dual role, that of Mason and as the actual murderer, Grimes. Martel appeared in the Star Trek episode "Amok Time" (1967) as T'Pring, Mr. Spock's wife, and the original The Outer Limits episode "Demon with a Glass Hand" (1964).
Martel played the princess Sarafina on Have Gun – Will Travel, the evil witch Malvina on Bewitched, the French Underground contact Tiger in five episodes of Hogan's Heroes (1965 - 1971), a female cosmonaut on I Dream of Jeannie, a Hungarian immigrant Magda on The Fugitive episode "The Blessings of Liberty" (1966), and, memorably, as the nurse who repeatedly utters the sinister phrase "Room for one more, Honey!" at the entrance to a hospital morgue and as the stewardess at the door of a doomed airplane in the Twilight Zone episode "Twenty-Two".
Other shows on which Martel appeared included The Man from U.N.C.L.E., The Untouchables, Mission: Impossible, Here Come the Brides, The Wild Wild West, Battlestar Galactica, The Monkees, Mannix, and The Six Million Dollar Man.
Martel had roles in such films as Angels from Hell (1968) and Chatterbox (1977). She appeared as a featured actress in the Gunsmoke episode titled "The Squaw" (1975). In 1974, Martel also appeared as "Tasha Martelle", playing secretary "Marty Bach" (eventual mistaken murder victim) in an episode of The Rockford Files (season 4), Episode 2, titled "Trouble in Chapter 17".
Martel received top billing when she starred as the commandant in charge of the Russian road crew in Zoltan, Hound of Dracula (1978), although it was only a bit part lasting less than five minutes of the 97-minute movie. She received credit in a font so large that it was almost twice as large as that used for Reggie Nalder or Michael Pataki, the leads who occupied most of the screen throughout the movie.
She appeared in the Star Trek webisode "Of Gods and Men" in the final scene as a Vulcan priestess initiating a marriage ceremony between Uhura and Vulcan native Stonn (a character from the episode "Amok Time", played by original actor Lawrence Montaigne). Martel played Gloria, mistress of murder victim Tony Goodland (Bradford Dillman), in the Columbo episode "The Greenhouse Jungle" (1972).
Martel semi-retired from acting in the mid 1980s, but continued to work sporadically in acting after that. She appeared in several episodes of TV and in some unreleased TV pilots in the early 2000s. She stated in interviews that even in her early career, she got most of her work via word of mouth and not through talent agents. In her later years, she often remarked, "I don't have a good agent who will get me the plum roles."
Before her death, Martel was one of the narrators for the 2015 documentary film Unity, which was released on August 12.
Martel attended the Performing Arts High School in New York, on which the movie Fame was based, graduating in 1953. She later studied method acting and was a member of The Actors Studio. She remained friends with Sidney Lumet and Anthony Quinn throughout their lifetimes.
Martel married and divorced three times. Her first marriage was to Robert Palmer, with whom she had one son, Adam Palmer. Her second marriage was to actor Jerry Douglas, with whom she had two children, Avra Douglas and journalist and designer Jod Kaftan. Her third marriage was to Matthew Schoen. She had three grandchildren.
In her later years, Martel wrote a screenplay, Whisper Into My Good Ear, based upon the one-act play of the same title by William Hanley. She had also begun work on a second screenplay, Mrs. Dally Has a Lover, also by Hanley. Unfortunately, neither was produced, although Edward James Olmos was slated to direct Whisper Into My Good Ear. Maximilian Schell and Max von Sydow were slated to play the leads. Anthony Quinn was her original choice to play one of the leads and was learning the lines shortly before his death.
Martel reportedly dated James Dean and Cary Grant. She appeared in the Robert Altman film The James Dean Story (1957) and did many interviews in the years following his death for such networks as the BBC.
She was a regular at Star Trek conventions worldwide from 1972 to 2014. Her last convention appearance was at TrekTrax Atlanta (later renamed Treklanta) in Atlanta, Georgia, on April 25–27, 2014.
On August 12, 2014, Martel died from heart bypass surgical complications at a hospital in Santa Monica, California. She had been battling breast cancer for the last five years of her life, although this was reportedly not the cause of her death. She was survived by her children and two of her three grandchildren.