George P. Dog (better known as Barnyard Dawg) is usually seen sleeping in his kennel at a cartoon's beginning, with Foghorn provoking him by slapping his hindquarters with a wooden fencepost, setting the stage for Dawg to seek vengeance.

Beginning with the 1949 cartoon Henhouse Henery, Foghorn would often perform a verse from the Stephen Foster song "Camptown Races", softly humming the lyrics while loudly singing the refrain "Doo-Dahh! Doo-Dahh!", and ending the verse, again loudly, with "Ohh, Doo-Dahh Day!"

Foghorn fancies himself a mentor figure to the younger roosters, especially Eggbert (or Egghead Jr.), often 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."

Foghorn is depicted as a tall, overweight rooster with a Southern accent.

His first name "Foghorn" is indicative of his loudmouthed personality, while his surname "Leghorn" refers to a particular Italian breed of chicken.

In Lovelorn Leghorn (1951), Miss Prissy is set on finding a husband and in Of Rice and Hen (1953) she is looking to have children. However, in Little Boy Boo (1954) she has a child (Egghead Jr.) who Foghorn takes under his wing in order to impress the widowed hen.

Foghorn makes numerous appearances in Tiny Toon Adventures, appearing as Acme Looniversity's Professor of Hound Teasing, Baseball Coach and an obnoxiously loud Librarian.

Foghorn's first appearance was in the 1946 Henery Hawk short Walky Talky Hawky, in which he convinces the young chicken hawk that Barnyard Dawg is a chicken.

Fowlmouth is a young rooster with a New York accent and a tendency to explode into bleeped-out graphic swearing whenever things don't go his way. His mentor, not surprisingly, is the equally loud (if less graphic) Foghorn Leghorn.

He is easily the tallest of all the regular Looney Tunes characters.