Fans of Marvel's Cinematic Universe have probably noticed that Thanos' quest for the Infinity Stones hasn't gone as planned. His underlings have repeatedly failed him, spurring him to take matters into his own hands. The mid-credits scene of "Avengers: Age of Ultron" showed Thanos grabbing his own Infinity Guantlet and preparing to collect the stones himself. But when will he actually do that?

"Avengers: Infinity War -- Part I" is due out in 2018 with "Part II" set to follow up in 2019. Apart from Thanos actually employing the Stones to wreak havoc on the universe, the films will not be a direct adaptation of the 1991 "Infinity Guantlet" story. That means it's unlikely that the Mad Titan will have collected all of the stones by the time "Part I" rolls around. In fact, he may not complete his Infinity Gauntlet until the beginning of "Part II" so as to draw out the drama. Even without the stones, Thanos is still one of the most powerful beings in the MCU. He has more than enough to give the Avengers a run for the money while biding his time.

Fans should expect Thanos to pop up in a handful of Phase 3 films as we slowly see him collect each stone. It's possible that he could be shown stealing the Tesseract from the Asgardian vaults in "Thor: Ragnarok," or taking the Orb from the Nova Corps in "Guardians of the Galaxy Vol. 2."

In the MCU, Thanos began with the Mind Stone but lost it once Loki failed to conquer Earth. That stone now resides in the android Vision.  Loki's failure also prevented Thanos from getting his hands on the Tesseract (aka the Space Stone). In addition, Ronan's double cross in "Guardians of the Galaxy" cost the Big Bad his shot at the orb (aka the Power Stone). Elsewhere, the Aether (aka the Reality Stone) from "Thor: The Dark World" is assumed to still be in the possession of Benicio Del Toro's Collector character. That leaves two Infinity Stones still to be introduced in Phase three: Time and Soul.

Excited yet?