Fran Cosmo is an American musician best known as a former lead singer of the rock bands Boston and Orion the Hunter.

Cosmo was first featured on guitarist Barry Goudreau's self-titled solo album in 1980, a prelude to the formation of Orion the Hunter in 1983.

Orion the Hunter released an album in 1984 on Columbia Records, which yielded the hit single "So You Ran".

In 1994, Cosmo was featured as the sole lead vocalist on the platinum Boston album Walk On, which reached #7 on the Billboard Charts and produced three hit singles, including "I Need Your Love", which climbed to #4 on the Mainstream Rock Chart, and "Walk On" that peaked at # 7 on the charts, and lasted for sixteen weeks.

He sang lead vocals on five of the album's songs and played guitar on one track as well.