Avengers assemble!

'Agents of SHIELD' Season 2: Cal To Explode Like Never Before, Responsible For Finale Death?

It's finally time - Avengers: Age of Ultron blasts into theaters today. For those new to the MCU - or those who need a little refresher - there is still time to binge watch some of Marvel's impressive slate.

So, which movies are an absolute must? Check out our list below to see what you need to watch before teaming up with Earth's Mightiest Heroes, and which you can save for a later date.

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Iron Man

It's always good to check out a heroes' origin story, but in the light of Age of Ultron, it's not entirely necessary. This film introduces viewers to Tony Stark and charts his evolution from rich genius to the arc reactor-powered, wise cracking Iron Man we have come to know and love. Also, JARVIS makes his first appearance, a key moment as Age of Ultron prepares to turn the AI into Vision.

Rent: Amazon, iTunes, Google Play, Vudu

Iron Man 2 (Must Watch #3)

Tony Stark goes up against Ivan Vanko while battling palladium poisoning. The second Iron Man outing introduces Black Widow - a key member of the Avengers - and James Rhodes, who becomes War Machine. Both these characters will play a role in Age of Ultron.

Rent: iTunes, Vudu

Thor

Head to Asgard as Thor is banished, powerless, to Midgard. An origin story for the demi-god, Thor may come in handy as Scarlet Witch forces the Avengers to relive their worst memories during Age of Ultron. There is a chance that a certain trickster will plague Thor's trip down memory lane.

Rent: iTunes, Amazon, Google Play, Vudu

Captain America: The First Avenger

This is the WWII-era origin story for the oldest of the Avengers - Steve Rogers. See the beginnings of HYDRA, meet Peggy Carter and a young Bucky Barns (AKA The Winter Soldier). Trailers have indicated that Scarlet Witch's meddling will take Steve's mind back to his heyday as he battles Nazis and the Red Skull.

Rent: iTunes, Amazon, Vudu

The Avengers (Must Watch #1)

Nick Fury launches the long gestating Avengers initiative as Loki makes the jump from Asgard to Earth while striking a deal with the MCU's overarching baddie, Thanos. The 2012 blockbuster brings Iron Man, Captain America, Black Widow, Hawkeye, Hulk, and Thor together for the first time and introduces viewers to Loki's scepter. Agents of SHIELD revealed that the scepter will pop up again during Age of Ultron, so this is some back story that is an absolute must.

Rent: Vudu

Iron Man 3

Tony Stark takes on the Mandarin while War Machine returns. Stark's surgery at the end of the film poses some interesting questions for Age of Ultron and viewers get to see a rather sleepy Bruce Banner as the Science Bros. reunite.

Rent: iTunes, Vudu

Thor: The Dark World

Cue the return of Loki. Once again Thor will bridge the gap between Midgard and Asgard as he hops through nine realms in order to remove the Aether from Jane Foster and keep the Dark Elves from getting their hands of the substance.

Purchase: Amazon, iTunes, Google Play, Vudu

Captain America: The Winter Soldier (Must Watch #2)

Caps teams up with Black Widow to battle the Winter Soldier and HYDRA. This film is Marvel's linchpin as the studio heads into Avengers 2. HYDRA's appearance has devastating effects for SHIELD, leaving Earth's Mightiest Heroes to deal with an increasingly unstable world as Age of Ultron begins. Keep you're eyes peeled for the mid-credits scene that introduces two new main characters for Avengers 2.

Purchase: iTunes, Google Play

Guardians of the Galaxy

Head into space with Peter Quill, aka Star-Lord, during one of 2014's biggest films. A band of ragtag criminals turn into heroes as they band together to take down Ronan. Viewers learn much, much more about Thanos but, otherwise, Guardians connections to Avengers 2 are few and far between.

Purchase: Amazon, iTunes, Google Play

TL;DR - The top 3 movies you should check out before heading out to see The Avengers: Age of Ultron:

1) Avengers

2) Captain America: The Winter Soldier

3) Iron Man 2

Click the video below to see a trailer for the May 1 release.