Foghorn is the leader of Blackie Cole's henchmen, played by Donald MacBride in The Invisible Woman. He was a very large man who earned his nickname thanks his deep bass voice. Along with Bill and Hammerhead, Foghorn was sent to America by Blackie to learn the secret of Professor Gibbs' invisibility machine. Foghorn attempted to gain entry to Gibbs' house by posing as a fellow scientist, but Kitty Carroll had overheard him talking to Bill and Hammerhead, and identified him as an imposter.
Later, while Kitty and the Professor were away visiting Richard Russell, Foghorn and his companions broke into Gibbs' laboratory and dismantled the invisibility machine, returning with it to Blackie's hideout in Mexico. After Hernandez reassembled the machine Blackie opted to test it out on Foghorn, but because it was missing a key component the test failed, and Foghorn lost his deep voice.
Read more about this topic: Minor Characters In Universal Monsters