Tom Mankiewicz, a screenwriter and premier script doctor who made his reputation working on such James Bond films as "Diamonds Are Forever," "Live and Let Die" and "The Man With the Golden Gun," has died. He was 68.

Mankiewicz, who received a controversial credit for rewriting the 1978 film " Superman" and its 1980 sequel, died Saturday at his home in Los Angeles after a brief illness, according to John Mankiewicz, his cousin.

Three months ago, Tom had undergone the Whipple operation, which is used to treat pancreatic cancer.

As a second-generation member of the Mankiewicz movie clan, he had often admitted he was intimidated by his family and its reputation. His father, Joseph L. Mankiewicz, the Oscar-winning writer and director of the 1950 film "All About Eve," was one of the most celebrated filmmakers of his era. His uncle, Herman J. Mankiewicz, co-wrote "Citizen Kane" (1941) with Orson Welles.

Trying to distance himself from his father in New York, Tom Mankiewicz headed for Hollywood in the early 1960s. Later, he said his last name made his journey both easier and harder — his phone calls were returned, but he worried that he got work because he was his father's son.

"So it took a while, until you suddenly started to realize that people were asking you because it was you," Mankiewicz told the Washington Post in 1985.

In 1970, Mankiewicz was hired to rewrite the script for "Diamonds Are Forever," the seventh film in the long-running series based on Ian Fleming's fictional spy James Bond.

In the Bond saga, Mankiewicz also wrote original screenplays for "Live and Let Die" (1973) and "The Man With the Golden Gun" (1974) and polished "The Spy Who Loved Me" (1977) and "Moonraker" (1979).

Known for a light and breezy writing style, Mankiewicz once said he had endured snickers for his association with the sexy Bond films. He told the Miami Herald in 1987: "I don't apologize for entertaining people."

Between Bond movies, he wrote and produced the 1976 film "Mother, Jugs & Speed," working with director Peter Yates, who called on him to rewrite "The Deep" (1977).

His most celebrated script doctoring may have been on "Superman," which starred Christopher Reeve. Director Richard Donner brought him in to rewrite the impossibly long script, and Mankiewicz stayed with the project for more than a year.

Donner called him a "creative consultant," and Mankiewicz's name appeared onscreen after the original writers'.

"The Writers Guild didn't want to give him a credit, but he definitely deserved a credit," Donner told The Times on Monday. "I probably wouldn't have made the movie if Tom hadn't come on to rewrite it."

"He brought a sense of reality to this comic book world," Donner said. "He created personalities, emotion and life" and gave the characters "a wonderful sense of humor. He did that in just about everything he did."

Donner also directed the 1985 film "Ladyhawke," for which Mankiewicz also received a screenwriting credit.

"He was one of the most enlightening characters that ever lived," Donner said. "He had an incredible, retentive mind.… He was one of the great storytellers of our industry."

Mankiewicz's nearly 20 writing credits include the screenplay for "The Eagle Has Landed" (1976). He co-wrote and directed the pilot for the ABC-TV series "Hart to Hart" and continued to have a hand in the series during its run.

In 1987, Mankiewicz debuted as a movie director with "Dragnet," which starred Tom Hanks and Dan Aykroyd.

Sheila Benson, then The Times' film critic, observed in her review that "there's real affection for the old show knocking around in this car-chase disaster movie."