Petunia Pig is a animated cartoon character in the Looney Tunes and Merrie Melodies series of cartoons from Warner Bros. She looks much like her boyfriend, Porky Pig, except that she has braided black hair and wears a dress.

Petunia was introduced by animator Frank Tashlin in the 1937 short "Porky's Romance ". The film is a parody of a 1932 Walt Disney cartoon called "Mickey's Nightmare ". Whereas Mickey Mouse marries his longtime girlfriend Minnie in that film, Porky's ouvertures toward Petunia bring him only the scornful laughter of his porcine paramour. Tashlin quickly adopted Petunia as a regular member of Porky's entourage and featured her in two more cartoons: "The Case of the Stuttering Pig " and "Porky's Double Trouble ", both in 1937. Voice actors Bernice Hansen and Shirley Reed each performed Petunia's voice in various shorts.

Bob Clampett was the only other Warner director to utilize Petunia after Tashlin left the studio in 1938. He first featured her in "Porky's Picnic ", a 1939 film that sees Porky tormented by his nephew Pinkie. Pinkie and Porky's encounters are always out of sight of Petunia, of course, so she naturally blames Porky for everything that goes wrong thanks to the practical-joking piglet. Petunia's largest and most involving role came in Clampett's 1939 short "Naughty Neighbors ". The film borrows elements from both the famous feud between the Hatfields and McCoys as well as Romeo and Juliet as Porky and Petunia's love for each other is stymied by their respective hillbilly families' mutual hatred. Despite her more prominent role in the short, Petunia is still nothing more than a supporting character; Porky remains the star.

As Porky's popularity was eclipsed in the late 1930s and early 1940s by brasher, funnier characters like Daffy Duck and Bugs Bunny, he was quickly relegated to a supporting player himself in new Looney Tunes and Merrie Melodies shorts. Petunia, already a bit player to Porky, fared much worse. She still appeared occasionally in Warners merchandising, but her tenure as a Warner Brothers player were mostly over. Nevertheless, she has enjoyed the occasional new role. She is a regular in the Baby Looney Tunes television series, for example.