If you think the portal scene from 2019's Endgame was the most epic crossover ever, think again
Avengers: Doomsday (2026) – Teaser Trailer | Robert Downey Jr.
You know what was perhaps the biggest, most climactic crossover in history? Here's a hint, it's not the portal scene from Avengers: Endgame, and don't even think about Deadpool & Wolverine. That's when Ben 10 teamed up with Rex in the one-hour special episode Generator Rex that aired on Cartoon Network.
The merger of the animated duo was so apical that it is still held special in the hearts of many millennials (and maybe some Gen Z with good taste). And rightfully so.
Captain America's fabled 'Avengers, assemble!' the command alone evoked a sense of harmony and an influx of overwhelming emotion in a fandom of more than thousands of people from around the world.
