In "Avengers: Infinity War," Iron Man (Tony Stark), portrayed by Robert Downey Jr., plays a significant role as one of the primary Avengers. Here's a brief overview of Iron Man's involvement in the film:

Iron Man is one of the founding members of the Avengers and a highly skilled inventor, billionaire, and superhero. In "Avengers: Infinity War," he faces the imminent threat of Thanos, a powerful cosmic warlord seeking to gather all six Infinity Stones to achieve his goal of wiping out half of all life in the universe.

Tony Stark, along with other Avengers and allies, including Doctor Strange, Spider-Man, and the Guardians of the Galaxy, unite to stop Thanos and his Black Order from obtaining the Infinity Stones.