Bruce Banner, also known as the Hulk, is a key character in 'Avengers: Infinity War'. He is a brilliant scientist who transforms into the Hulk, a giant, powerful green creature, when angered. In the film, Bruce struggles with summoning the Hulk after their defeat by Thanos. He plays a crucial role in assisting the Avengers with his intelligence and scientific expertise, especially in developing strategies and technology to combat Thanos and his forces. Despite his internal conflict, Bruce remains a vital member of the Avengers team.