A heffalump is a fictional creature mentioned in the Winnie the Pooh stories, both in Winnie-the-Pooh (1926) and later in The House at Pooh Corner (1928).

In the books, Pooh and Piglet attempt to bravely capture a heffalump in a trap. But no heffalumps are ever caught in their trap, and indeed no heffalump is ever met with in the course of the books. The sole actual "appearance" of heffalumps in the books come as Pooh tries to put himself to sleep. "[H]e tried counting Heffalumps [but] every Heffalump that he counted was making straight for a pot of Pooh's honey...[and] when the five hundred and eighty-seventh Heffalump was licking its jaws, and saying to itself, 'Very good honey this, I don't know when I've tasted better,' Pooh could bear it no longer." We learn nothing more about the nature of the beasts -- rather sensibly for an animal which does not even exist in the fictional world of Pooh et al. -- in the writings.

Although never explicitly stated it is generally thought that heffalumps are elephants from a child's viewpoint (with the word "heffalump" being a a child's attempt at pronouncing "elephant"). Even though it was never stated, E. H. Shepard's illustrations in A. A. Milne's original books depict heffalumps (as seen in Pooh's dreams) as looking very much like elephants. The heffalumps in the television series The New Adventures of Winnie the Pooh also look like elephants, albeit slightly cuddlier and less fierce elephants than those Pooh imagines in the books.

In the animated television series, most heffalumps are enemies of Pooh and his friends. They are known to steal honey, and are often associated with woozles. One particular heffalump named Heff was the dim-witted sidekick for Stan the Woozle, and he was afraid of Roo , because he thought Roo was a giant mouse (perhaps a reference to the Looney Tunes running gag of Sylvester mistaking Hoppy the Baby Kangaroo for a giant mouse). Being voiced by Chuck McCann , Heff sounded just like Bouncer Beagle from DuckTales. Piglet befriended a young heffalump named Junior in two episodes of The New Adventures of Winnie the Pooh.

Since in the 1950s heffalumps have gained substantial fame outside of the Winnie-the-Pooh stories. The term heffalump is commonly used to describe an elephant or a child view of an elephant.

The term heffalump trap is often used in politics for a trap that is setup to catch an opponent but ends up trapping the person who set the trap as happens to Winnie the Pooh in The House at Pooh Corner.

Heffalump is also used in other contexts including lie algebra and as a boy's name. In psychology heffalumps have been used as an example of an animal which exists in thoughts but not in reality.

Books featuring heffalumps include,

• Winnie-the-Pooh by A.A. Milne
• The House at Pooh Corner by A.A. Milne

There is also a music score called To Catch a Heffalump (1971) by Willem Frederik Bon .

Pooh's Heffalump Movie was released in 2005, and looks at the differences between the denizens of the Hundred Acre Woods and the Heffalumps who they fear as a mutual prejudice, cleared up after Roo becomes friends which a Heffalump named Lumpy. [1]