Foghorn Leghorn was directly inspired by the character of Senator Claghorn, a blustery Southern politician played by Kenny Delmar on Fred Allen's popular 1940s radio show.

Physically, Foghorn Leghorn is depicted as a very large rooster with a Southern accent; he is easily the tallest of all the regular Looney Tunes characters.

Foghorn often fancies himself a mentor figure to the smaller and younger characters he encounters, particularly Henery Hawk, tossing off bits of self-styled sagacity interjected with phrases like "Pay attention, son", or "Look at me when I'm talkin' to ya, boy", both of which are borrowed heavily from Senator Claghorn's vernacular.

But this proves to be Foghorn's worst trait, as his loud and fast mouth and propensity for over-explanation eventually annoys his intended subjects so much that, completely fed up with him, they end up hitting him over the head with a blunt object, yelling "Ahhhhh, shut up!"

Beginning with the 1949 cartoon Henhouse Henery, Foghorn frequently performs a verse from the Stephen Foster song "Camptown Races", softly humming the lyrics while loudly singing the refrain "Doo-Dahh!

Most of the Leghorn cartoons begin the same: Foghorn, humming "Camptown Races" to himself and carrying a wooden plank, sneaks up on Dawg while he is sleeping, often facing into his doghouse with his back protruding out the entry hole.

Despite their feud, Foghorn and Dawg manage to get along in a few instances, usually joining forces to defeat somebody who has caused problems for both of them (e.g. Daffy Duck in The High and the Flighty or a fox in Fox-Terror).