This Article Contains Spoilers - WARNING: This article contains major spoilers. If you do not wish to know vital information on plot / character elements in a story, you may not wish to read beyond this warning: We hold no responsibility for any negative effects these facts may have on your enjoyment of said media should you continue. That is all.
Future Mordecai is the secondary antagonist (later anti-hero) of the 2015 black comedy film, Regular Show: The Movie.
In Regular Show: The Movie, Future Mordecai killed Future Rigby in anger once their former science teacher Mr. Ross informed him how Rigby forged a fake letter from College University denying Mordecai's application just so they would remain as friends. Once Mordecai learned the truth, he became outraged by this and joined Mr. Ross' criminal empire and turned against his own friends since he would have had a better career and life if he was in College University.
A high school lab experiment went horribly wrong and accidentally created a TImenado and is on the verge of destroying the universe. Mordecai and Rigby go back in time as well as Pops, Skips, Benson, Muscle Man, and Hi Five Ghost just to stop this. However, Future Mordecai and Mr. Ross showed up to stop them later in the high school where they were trying to disable the time machine that Mordecai and Rigby's high school selves created.
Future Mordecai ended up having to sacrifice himself in order to protect Mordecai when Mr. Ross was about to kill him. Before Future Mordecai died, he confessed to Mordecai that he would have been a lot better off having friends instead of being successful.