Dexter's Laboratory: Ego Trip is an Annie Award-winning one-hour animated television special spawned from the Cartoon Network animated television series Dexter's Laboratory, produced by Hanna-Barbera (now Cartoon Network Studios) for Cartoon Network, and aired in 1999.
In the first time period he visits, Dexter finds a tall, skinny, weak version of himself working in office-designing cubicles, with Mandark as his rich, successful boss. The child Dexter unwittingly reveals the existence of blueprints regarding the Neurotomic Protocore from the beginning of the movie, and Mandark steals it after the two Dexters move forward in time.
In the second time period, the two Dexters meet their much older self, a wizened senior citizen Dexter about the same height as the child Dexter (and Mandark's brain in a vat who cannot do anything other than complain about his situation). All the technology from the blueprints has been implemented, creating a utopian society where anything can be materialized with the power of the mind. The old Dexter can't remember how he saved the world, so they travel back in time to find out.
In the third time period, which appears to take place between the first and second time periods, they find a dystopic world where everyone is stupid and fire and technology are forbidden, controlled by Mandark thanks to the Neurotomic Protocore. They meet action hero Dexter (Jeff Bennett), who is tall, muscular and bald (senior citizen Dexter, it turns out, wears a wig), as well as having grown a large beard and huge muscles while digging underground after Mandark stole the plans. They go back to Dexter's laboratory and build a giant robot to invade Mandark's fortress. Reaching there, they are faced by the monstrously corpulent dystopian Mandark, who has summoned versions of himself from other time periods to oppose the Dexters. A battle royale ensues, with each Dexter fighting the Mandark of his own time period.
After a battle between the Dexters and Mandarks, Dee Dee (Kat Cressida) saves the world by wandering in from the open time gate and pressing the button to reverse the waves of the Neurotomic Protocore, thus creating the utopian world. The Dexters, overcome with rage, create a group of robots and tell them to "destroy the one who saved the future", and send them back through the time machine to take care of Dee Dee, unwittingly setting the whole series of events in motion. When Dexter notices this fact, he decides to ignore it and goes to eat lunch.