That's All Folks is the closing title card on almost every Looney Tunes story. It was first used by Bosko and more commonly by Porky Pig in the Golden Age of Animation, before the standard script logo on the bullseye came to use. It had many variations over the years, depending on the situation, which is similar to the Couch Gag opening of The Simpsons.
Bosko was the first character to say the phrase starting with the first official Looney Tune, Sinkin' In The Bathtub. His cartoons ended with him running in front of a sign reading "A Looney Tune" and saying "That's all, folks!"
The Merrie Melodies of the same time would feature the star of the cartoon running in front of a drum reading "A Merrie Melody", only they would say "So long, folks!" Unlike Looney Tunes, these would change with every cartoon.
It wasn't until 1936 that both series started to use the now-famous script sign-off. The Looney Tunes shorts depicted the text being written on a black background, while the Merrie Melodies had it written over the bullseye. The first Looney Tunes to feature it were released in early 1936.
In 1940, Confederate Honey was released and the ending had the finalized "That's all Folks!" version which is being used today.
The first design was in 1936 with a lowercase "f" instead of an uppercase "F" in "Folks". In 1938 it was changed again. In 1940, WB created the finalized version.
1937's Rover's Rival made history by introducing Porky Pig's now-iconic sign-off. As an instrumental version of "The Merry-Go-Round Broke Down" played in the background, Porky Pig would pop out of a drum and say "Th-th-that's all, folks!" This was used until 1946, when the Looney Tunes series too adopted the standard script logo on the bullseye like Merrie Melodies.
Starting in 1964 (beginning with Senorella and the Glass Huarache), the opening and closing titles were redesigned and the phrase was dropped for both series. This change stuck until the series ended in 1969.
The phrase has returned in most Looney Tunes productions from the 1970s onwards.
Porky Pig returned to signing off the Larry Doyle-produced Looney Tunes in 2003.
The Looney Tunes Show featured its own variations on the gag.
- The ending of Daffy Duck's debut cartoon, Porky's Duck Hunt, depicts the duck frolicking around a prewritten "That's all folks!" end card.
- In the end of The Major Lied till Dawn, the elephant says to the audience "That's all, folks!" then the "Merrie Melodies" and "Produced By Leon Schlesinger" credits appear at the top and bottom of the screen as a fast version of the Merrie Melodies ending theme music plays over it.
- The Old Grey Hare ends with Bugs handing Elmer Fudd a lit firecracker. After the iris out, the "That's all Folks!" title card appears, prewritten, and the firecracker exploding off-screen, shaking the on-screen title card.
- Hare Tonic and Baseball Bugs end with Bugs Bunny bursting out of the Looney Tunes drum to say "Eh, and that's the end!"
- A few Blue Ribbon Merrie Melodies reissues from 1952-1953, such as The Bashful Buzzard and Daffy Doodles, replaced "That's all folks!" with a generic "The End" card with no animation.
- At the end of Stop! Look! And Hasten! the Road Runner spells out the "That's All Folks!" ending card in smoke as he runs on the road.
- The Bugs Bunny Road-Runner Movie begins with the "That's all Folks!" signoff. Once it finishes, Bugs places a "NOT" between the "That's" and "All" to show the audience that the movie is just beginning. At the end of the movie, as the signoff starts writing itself, Bugs pops on to stop it. It then erases and writes itself as "That's not quite all Folks!", and Bugs starts the ending credits. As the credits finish rolling, the title fades in as "That's really all Folks!"
- In Old Glory, the ending credits fade in over the waving flag and "The End" appears rather than "That's all Folks!".
- At the end of the edited-for-TV version of Duck Dodgers and the Return of the 24½th Century, when the "That's all, folks!" ending rings appear, Marvin the Martian pops out and says to the audience "Don't worry, folks. After all, it's only a cartoon".
- Box Office Bunny ends with Bugs trapping Daffy and Elmer in a slasher movie and, afterwards, watching their predicament in the cinema while eating popcorn. After the cartoon irises out and the title card finishes with it's ending credits as normal, Daffy and Elmer break out through the title card, screaming and running for their lives. Bugs appears in the hole of the broken card and smiles to the camera as he says "And that's all, folks!".
- At the post-credits of Invasion of the Bunny Snatchers, a creepy-looking, Monty Python-esque impostor of Porky Pig pops out of the drum saying a very distorted "Th-Th-Th-Th-That's all, folks!". When Bugs see this, he angrily kicks away the Porky impostor and puts the real Porky Pig into the broken drum. The real Porky then ends the cartoon with his signature "Th-Th-Th-That's all, folks!" line.
- At the post-credits of Space Jam, Bugs, Daffy and Porky argue on whose role to say the "That's all, folks!" line (Bugs firsts says that line, but Porky reprimands him that's his line, but just as Porky is about to say the "That's all, folks!" line, Daffy arrogantly interrupts Porky, only to get knocked off the bullseye rings by the Nerdlucks who perfectly say "That's all, folks!" all in unison). Then Michael Jordan temporarily pulls up the title card like a shade and asks the audience "Can I go home now?" before pulling the title card back to its original position. The "That's all Folks!" script writes itself on the bullseye rings before it fades out to black.
- Looney Tunes: Back in Action ends with Porky attempting to say his catchphrase, only to hesitate when the lights turn off. Eventually, he gives up and angrily says "Eh-h-h-h, go home, folks."
- Looney Tunes: Rabbits Run ends with the "That's all Folks!" script writing itself above the rings in yellow, after which Porky pops out of the bullseye and says his signature sign-off ("Th-Th-That's all, folks!"), only for him to find Daffy having walked in on the set with a corn dog in his hand. Daffy says, in a somewhat rude manner, "Interesting!", during which Porky becomes exasperated and whacks him with a frying pan as he takes a bite off his corn dog.
- Taz-Mania episode "Willie Wombat's Deja Boo-Boo" ended with this line, with Taz doing Porky's signature stutter.