Carl Stalling composed/adapted/arranged the music for the Looney Tunes. Warner Bros had their own staff orchestra who were getting salaries whether they worked or not, so WB let the guys in the Termite Terrace make use of them. If you scroll down from my link, you’ll find a partial list of songs he adapted for cartoons.
One of my favorite parts of my developing opera fandom is being pleasantly surprised every time I’m enjoying a new-to-me opera and having some bit of music come up and thinking, “Oh, I recognize this from Bugs Bunny.”
Merrie Melodies’ I’m Wearin’ My Green Fedora (for Dora, for Dora); Drink To Me Only With Thine Eyes; I Love to Sing-A, It’s As Easy (As Falling Off A Log).
I can’t help but be reminded of a fairly obscure old Saturday Night Live fake television commercial from the episode that Jeremy Irons did. He was pitching a compilation of classical pieces that had been featured prominently in Looney Tunes. Kind of amusing, if only to get the opportunity to see Irons subverting his typically grave and dignified image by singing, “Kill the wabbit!” along with the accompanying Wagner selection.
I’ll just complement that with “Largo al Factotum” from Rossini’s “The Barber of Seville”. The song that Giovanni Jones is trying to rehearse while Bugs plays the quoted song, which Giovanni starts to sing as well.