The 58-year-old actor is close to signing on to play the role of Bonaparte, an ex-mercenary, who comes to the assistance of the team of hired soldiers in the big budget blockbuster action movie, Deadline reported.
The part was initially offered to Cage, who was only expected to have a small cameo since filming is already underway for the project.
Grammer will appear alongside an all-star cast of Hollywood's finest musclemen, including Sylvester Stallone, Arnold Schwarzenegger, Jason Statham, Harrison Ford, Mel Gibson, Antonio Banderas, Jet Li, Dolph Lundgren, Wesley Snipes and Terry Crews, as well as model-and-actress Milla Jovovich.
The actor, best known for his TV shows 'Cheers' and 'Frasier', has made a move into action films of late.
He also landed the role of the villain in Michael Bay's alien robot movie, "Transformers: Age of Extinction", in which he will play scheming counter intelligence officer Harold Attinger, a character who is thought to hatch a plan to use Cybertronian technology as weapons research for mankind.
"The Expendables 3" is due for release on August 15, 2014.