"Have You Seen This Snail?", also known as "Where's Gary?", is the third episode of the fourth season and the 63rd overall episode of the American animated television series SpongeBob SquarePants. Its animation was directed by supervising director, Alan Smart and Tom Yasumi, and written by storyboard director Aaron Springer and supervising producer Paul Tibbitt. The episode originally aired on Nickelodeon in the United States on November 11, 2005. Actress and comedian Amy Poehler guest starred in the episode as the voice of Grandma. It is the first double-length episode to not be hosted by Patchy the Pirate in a framing device.

The series follows the adventures and endeavors of the title character and his various friends in the underwater city of Bikini Bottom. In this episode, Gary, SpongeBob's pet sea snail, runs away from home after feeling neglected by a distracted SpongeBob and is adopted by a new owner. After realizing the error of his ways, SpongeBob sets out with his best friend Patrick to search for his adored pet and bring him back to his rightful home.

The episode garnered eight million viewers, achieving the highest number of cable television viewers aged six to eleven years old for 2005. "Have You Seen This Snail?" received generally positive reviews from television critics upon release.

Musician Stew performed the song "Gary's Song", which was later performed as an instrumental by Kenny G for The SpongeBob Movie: Sponge on the Run.