James expressed deep sadness, saying he felt as if "a part of me was broken," Variety reported.

James and Landau were close producing partners for over 30 years, working together on landmark films such as 'Titanic' and the 'Avatar' series.

“The Avatar family is saddened by the passing of our friend and leader, Jon Landau,” the director told Variety. His eccentric humor, personal magnetism, great generosity of spirit and fierceness would have kept him the center of our Avatar universe for nearly two decades.

James praised Landau's skill and love for pushing the boundaries of filmmaking, as well as his admirable personal qualities.

“His legacy is not just the films he produced, but the personal example he set, caring, inclusive, tireless, insightful and completely unique. He made great films, not by wielding power but by spreading warmth and the joy of making movies. He inspires all of us to be our best every day,” James said.

“I have lost a dear friend and my closest colleague of 31 years. A part of me is broken.”

James and Landau began their professional relationship 30 years ago when Landau, as a film executive at 20th Century Fox, oversaw Cameron's 1994 action comedy 'True Lies,' starring Arnold Schwarzenegger.

When Landau left Fox, Cameron asked him if he wanted to read the script of a secret project with the code name 'Planet Ice'. Landau joined the cast of the film, which was released in 1997 with the title 'Titanic' and became the first film in history to cross the $1 billion mark at the global box office.