Alan Silvestri has been composing music for television and video since the early '70s. He got his start dabbling with police action/dramas by scoring three episodes of Starsky and Hutch. He landed a regular gig composing the music for motorcycle cop serial show CHiPS in 1972.
What catapulted Silvestri to prominence, however, was his frequent collaboration with director Robert Zemeckis. Silvestri and Zemeckis have teamed up for 14 films, notably the Back to the Future trilogy and 1994's Forrest Gump, for which Silvestri was nominated for an Oscar and Golden Globe for Best Score, (ulimtately losing out to Hans Zimmer for The Lion King on both counts.)
Forrest Gump was a movie so hard to classify, even the critics were at a loss to describe it accurately. Pauline Kael hated it, Roger Ebert loved it, but he wasn't sure why! The film showed a different side of Tom Hank's acting abilities, and Silvestri's score perfectly captured the simplicity and wonder of the titular character.
Silvestri is noted for his work in action films, too. His scores for the two Predator movies established him as a go-to composer for recent action franchises like The Avengers series.