Fellowes said he will set the record straight on William Murdoch, first officer on RMS Titanic, in his new four-part miniseries on the 1912 disaster for the U.K.'s ITV1.
Also read: Cameron's Lessons Learned From 'Titanic'
Cameron's Oscar-winning 1997 blockbuster — due for a 3D re-release next month –portrayed Murdoch as a coward who shot passengers before taking his own life. Fellowes told the U.K.'s Radio Mag that in fact Murdoch, who went down with the ship when she sank after hitting an iceberg, was credited with launching the lifeboats that saved 75 percent of the survivors.
Fellowes told the magazine: "That was very unfair how Murdoch was depicted. He wasn't cowardly.
"He fired the pistol to just stop a potential riot. It was suddenly getting out of hand, and he fired it in the air. That's not being cowardly."
Fellowes added: "I don't think you can just say, 'Well, we'll make this guy a villain — he'll do."
The "Gosford Park" writer told the magazine: "I think with real people you have a kind of imperative to be true to who they were.
"I don't think you can take someone who was moral and decent and make them do something immoral and indecent.
"I would feel uncomfortable doing that. So we do have Murdoch, and we have him firing a pistol…(But) there is a little bit of setting the record straight."
In 1998, Twentieth Century Fox gave $8,000 to a fund commemorating the Titanic's first mate after his family and neighbors objected to the movie's portrayal of him.