At today's Marvel Studios event, Marvel Studios showed a very brief teaser for Avengers: Infinity War Part 1 & Part 2. The Avengers: Infinity War teaser starts with a close-up of the Infinity Gauntlet filled with Infinity Stones.
Then, the video shows the Infinity Gauntlet slowly moving backwards to reveal Thanos' face. The video then fades away from Thanos to reveal the Marvel Avengers: Infinity War logo.
Infinity War is based on the classic Marvel Comics stories that begin with the Infinity Gauntlet event. Thanos first appeared in the after-credits scene of the Avengers, and the made a brief appearance in Guardians of the Galaxy, played by Josh Brolin.
Avengers: Infinity War Part I is scheduled to be released in movie theaters on May 4, 2018, and Avengers: Infinity War Part II is scheduled to be released in movie theaters on May 3, 2019.