The original Clu was created by Kevin Flynn
to seek out evidence that ENCOM engineer Ed Dillinger stole several of Flynn's video game designs. In the original Tron
film, Clu is unfortunately caught and assimilated into the Master Control Program (read: tortured to death).
Flynn later created a new version of the program, Clu-2, to serve as a de facto leader of the Grid; though as its creator, Flynn has ultimate control at the outset of Tron: Evolution
. However, Clu-2 ultimately finds a way to steal power away from Flynn and reign supreme as a sinister tyrant, setting up the plot of Tron: Legacy