Terrence Howard Claims 'Triumph' Producers Broke Promises, Threatens to Sue

Terrence Howard's hired some big legal guns to wrestle with producers of his new movie, "Triumph" ... claiming they don't have his consent to use him in the film, which has already been released -- and that's a problem.

TMZ's obtained a cease and desist letter sent by Howard's legal team to employees at Cinemark, Digital Ignition Entertainment, Argonaut Entertainment Partners and others, alleging the actor's name, image and likeness have been used in connection with the feature film without his permission.

According to the letter, signed by attorney Michael Saltz ... Howard's involvement with the movie -- which co-stars RJ Mitte of "Breaking Bad" playing a high school wrestler with cerebral palsy -- was "conditioned upon the satisfaction of material monetary and non-monetary promises made by the producers, which never happened."

Howard's attorneys claim these producers acknowledged as recently as April 15 that Howard's consent had not been obtained and "Triumph" could not come out until they got a signed release ... but the movie was theatrically released on April 30 anyway.

On top of that, Howard's heavily featured in promos for the film ... which makes sense since he plays the wrestling coach.

The letter goes on to threaten Argonaut with legal action if it continues involving Howard with "distribution, advertising, promotion, and/or exhibition of 'Triumph' in any manner" ... claiming it's a violation of his publicity rights.

Digital Ignition Entertainment tells us, "The producers made this film with a mission to help advance awareness of Cerebral Palsy and to do our part to promote inclusion in film.  We couldn’t be more proud of the job our cast and crew did to highlight the remarkable accomplishments of the writer of the film, who has Cerebral Palsy, and the lead actor of the film, RJ Mitte, who is also diagnosed with cerebral palsy."