John Landau, the Oscar-winning producer who worked closely with director James Cameron on three of the biggest blockbuster films of all time, "Titanic," and two "Avatar" films, has passed away at the age of 63.

The Landau family announced his death on Saturday, without providing a cause of death.

Landau's partnership with Cameron led to three Oscar nominations and a win for Best Picture for "Titanic" in 1997. Together, the duo represents some of the biggest box office successes in film history, including "Avatar" and its sequel, "Avatar: The Way of Water."

Landau's career began in the 1980s as a production manager, gradually rising through the ranks, where he worked as a co-producer on "Honey I Shrunk the Kids" and "Dick Tracy."

He took on the role of producer for "Titanic," Cameron's lavish epic about the infamous maritime disaster that occurred in 1912. The gamble paid off, as "Titanic" became the first film to surpass $1 billion in global box office revenue and won 11 Oscars, including Best Picture.

Landau said while accepting the award with Cameron, "I can’t act, I can’t write, and I can’t do visual effects, so I think that’s why I produce."

Their partnership continued, with Landau becoming one of the top executives at Cameron’s Lightstorm Entertainment. In 2009, the duo released "Avatar," a sci-fi epic filmed and shown in pioneering 3D technology, which surpassed the box office success of "Titanic," while remaining the highest-grossing film of all time.

The second part of the film, "Avatar: The Way of Water," ranks third on the list.

Landau was a key player in the "Avatar" film franchise, which faced multiple delays in the release of "The Way of Water." Landau advocated for the second installment's progress and Cameron's ambitious plans to shoot multiple sequels simultaneously to keep the franchise alive.

Landau told the Associated Press in 2022, just months before the release of the second part: "Although a lot has changed, there is also a lot that hasn’t changed. One of the things that hasn’t changed is: Why do people turn to entertainment today? Just as they did when the first Avatar movie came out, they do it to escape, to escape from the world we live in."

Alan Bergman, co-chairman of Disney Entertainment, said in a statement: "John was a visionary, and his extraordinary talent and passion brought some of the most unforgettable stories to life on the big screen. His remarkable contributions to the film industry have left an indelible mark, and he will be greatly missed. He was creative and successful. He’s a producer but an even better person and a true force of nature who inspired everyone around him."

Landau was appointed senior vice president of feature films at 20th Century Fox when he was 29 years old, overseeing successful movies including "Home Alone" and its sequel, as well as "Mrs. Doubtfire" and "True Lies," where he began working closely with Cameron for the first time.

Landau was also influential in bringing the adapted manga "Alita: Battle Angel" to the big screen in 2019. Cameron supported the project, but his commitments to "Avatar" prevented him from directing it. Instead, Landau worked with director Robert Rodriguez to complete the film.

Landau was born in New York City on July 23, 1960, the son of film producers Eli and Edie Landau. The family moved to Los Angeles in the 1970s, and Landau graduated from the USC School of Cinematic Arts.

Edie Landau passed away in 1993. Eli Landau, the Oscar-nominated producer for films such as Long Day’s Journey Into Night, Hopscotch, and The Deadly Game, died in 2022.

John Landau is survived by his wife Julie, with whom he had been married for nearly 40 years. Their children are Jimmy and Judy, along with two sisters and a brother.