Movies To Watch Before ‘Avengers: Infinity War.’

If you didn't plan ahead of time to watch all 18 Marvel Cinematic Universe movies before "Avengers: Infinity War" hits theaters TODAY. 

Here are the must-watch Marvel movies to see. 

1. Iron Man

2. The Avengers

3. Avengers: Age of Ultron

4. Guardians of the Galaxy

5. Captain America: Civil War

6. Thor: Ragnarok