Hippety Hopper is an animated cartoon character in the Warner Bros. Looney Tunes series of cartoons.

Robert McKimson introduced Hippety Hopper in "Hop, Look and Listen " (1948), which created the mold into which future Hippety Hopper cartoons would fall: baby kangaroo Hopper escapes from the zoo, the circus, etc., and is mistaken for a giant mouse by Sylvester. Sylvester tries to capture and eat his "prey", but the innocent and infantile Hippety mistakes Sylvester's predations for a game -- a game of rough-housing, to be exact. Sylvester is repeatedly punched, kicked, and pounced, but each failure only cements his will to have the "mouse" for lunch. The cat's dignity will suffer no less. The character would later return in McKimson's "Pop 'Im Pop " (1950) in which proud papa Sylvester boasts of his mousing skills to his son, Sylvester Junior. Sylvester mistakes Hippety Hopper once again for a giant mouse, and the baby kangaroo promptly beats the cat to a pulp. Junior is mortified, but the true victim is Sylvester, humiliated by a mere "mouse" in front of his own son.

McKimson would continue the Sylvester/Hippety Hopper series for 16 years, varying it slightly from cartoon to cartoon. In "Bell Hoppy " (1954), for example, Sylvester must hang a bell around a mouse's neck in order to join the "Loyal Order of Alley Cats and Mousing and Chowder Club". In "Lighthouse Mouse ", Sylvester must guard a lighthouse from the baby kangaroo who wants nothing more than to turn it off. The central theme is always the same: Sylvester is shamed for his failure to capture a simple "mouse".

The Hippety Hopper/Sylvester cartoons ended in 1964 when the Warner Bros. studio closed its animation unit. The character continues to appear in Looney Tunes marketing and other projects, such as the 1996 film Space Jam.