Jack Horner may refer to:

• "Little Jack Horner", a nursery rhyme

• Jack Horner (activist) (born 1922), Australian author and activist in the Aboriginal-Australian Fellowship
• Jack Horner (baseball) (1863–1910), American professional baseball player
• Jack Horner (journalist) (1912–2005), Gordon John Horner, Minnesota sportscaster
• Jack Horner (paleontologist) (born 1946), American paleontologist
• Jack Horner (politician) (1927–2004), John Henry Horner known as "Jack" or "Cactus Jack", member of the Canadian House of Commons
• Jack B. Horner (1922–2009), Pennsylvania politician

• "Big" Jack Horner, a character from the 2022 film Puss in Boots: The Last Wish
• Jack Horner, the fictional porn director in the 1997 film Boogie Nights
• Jack Horner (comics), a character from the comic book, Fables, created by Bill Willingham, based on the nursery rhyme character
• Little Jack Horner, the protagonist of the nursery rhyme "Little Jack Horner"

• Jack Horner (racehorse) (born 1917), 1926 Grand National winning horse

• All pages with titles containing Jack Horner
• John Horner (disambiguation)
• Horner (disambiguation)