In an interview with Scotland on Sunday, Gibson acknowledged Wallace was "romanticized a bit" in the movie.
"He was a monster. He always smelled of smoke; he was always burning people's villages down," Gibson said. "He was like what the Vikings called 'a berserker.' We shifted the balance because someone's got to be the good guy against the bad guy; that's the way stories are told."
Wallace did well by Gibson. He produced, directed and starred in the 1995 film, which won Oscars for Best Picture and Best Director.
Some historians suggest Gibson has swung too far the other way in his views on Wallace. Fiona Watson, author of a Wallace biography, said he undertook diplomatic missions to get support for Scotland.
"It's fascinating," she told the newspaper. "After 15 years, he's giving us the other version of the myth, the knuckles dragging across the floor one, which is equally untrue. The real man surely lies in between."