Below are the essential must-watch Marvel movies to be sure you're familiar with before strolling into the — I'm sorry — gauntlet.

THE MCU — Perhaps you haven't planned ahead enough to watch all 18 Marvel Cinematic Universe movies before "Avengers: Infinity War" hits theaters on April 27. But you could make time for a simple six-movie marathon, right?

Below are the must-watch Marvel movies to be sure you're familiar with before strolling into the — I'm sorry — gauntlet of "Infinity War."

"Iron Man"

It was the first movie in the Marvel Cinematic Universe, and it remains one of the best of the entire franchise. Robert Downey Jr. is masterful in his first turn as Tony Stark, and although he has grown into the character over the past 10 years, nothing beats this fun romp.

"The Avengers"

You need to see the team up and banter of the original "Avengers" to appreciate the way it evolves as the group continues to come together. Some of the best lines of dialogue in the whole series are in this movie, as Iron Man, Thor, Captain America and the Hulk join S.H.I.E.L.D. in saving the world.

"Avengers: Age of Ultron"

Unfortunately, it's not as good as the first "Avengers" movie. But you get to meet some additional Avengers (Falcon, Vision, the Maximoff twins) and enjoy some good moments of the whole gang just kicking it after a party, seeing who can lift Thor's hammer.

"Guardians of the Galaxy"

This movie reinvented the Marvel wheel, promising great soundtracks and more jokes in the movies that came after it. It's a space-pirate jaunt through the galaxy with some characters you will fall in love with despite the fact they're a raccoon and a talking tree.

"Captain America: Civil War"

This is basically a mini-Avengers movie, but you get to see them all fight each other! Introducing Spider-Man to the group, it captures the comic book tone perfectly, with lots of humor tied into a pretty grave and emotional storyline.

"Thor: Ragnarok"

This is my personal favorite of all the options, and for that reason alone I recommend it. It's hilarious, fresh, neon and nonstop goodness. Jeff Goldblum and Cate Blanchett are playing on opposite ends of the villain spectrum and are both so incredible. The jokes are spot on.

If you're a purist, or if you're watching for research purposes, you could consider watching each of the Marvel movies that contain an Infinity Stone:

The Infinity Stones are included in "Captain America: The First Avenger," "Thor: The Dark World," "The Avengers," "Guardians of the Galaxy" and "Doctor Strange."

About half of those movies are mediocre, so watch them at your own risk.