Stan Lee has declared war over the new "Conan the Barbarian" movie -- claiming the rights to the character were stolen from him ... and now he's demanding 100% of the proceeds from the flick.
Lee ... who claims his company, Stan Lee Media, bought the rights to all things Conan in 2000.
According to a lawsuit filed in federal court in L.A., Lee claims his company went bankrupt in 2001 -- which would have prevented anyone from taking the rights to Conan away from him.
But Lee claims he was betrayed by his former lawyer, who made an illegal deal to move the rights to another company behind Lee's back ... a company that later gave the green light to make the new Conan movie.
Now, Lee wants a judge to rule that he is still the rightful owner of Conan ... and he's demanding every single cent the movie makes.