Hemulens are a species of characters in the Moomin series of books by Swedish-speaking Finnish author Tove Jansson. Hemulens feature in several of the books. In the original Swedish, the name of this species is hemul (plural hemuler), and -en is a definite article, so "hemulen" means "the hemul".
One Hemulen collects butterflies, and another is an avid skier. A female Hemulen raised Moominpappa in an orphanage, and later Moominpappa encountered her aunt, who looked confusingly like her. In Comet in Moominland there appears a Hemulen who is an avid stamp-collector. In the following book, Finn family Moomintroll, he is initially depressed because he has acquired a copy of every stamp in the world, so that his life has no more meaning. He then realises he can take to botany, and collect plants, whereupon he brightens up.
Hemulens tend to have obsessive personalities, devoting themselves solidly to one interest, whether it be skiing, stamp-collecting, butterflies, or whatever. They tend also to be oblivious to the feelings and opinions of others. Other characters frequently find the Hemulens annoying or overwhelming, as they can be somewhat loud, bossy, abrasive and insensitive. However, they are well intentioned and usually have other redeeming qualities. Hemulens resemble Moomintrolls, but are taller, always grey, and have an even longer nose than moomintrolls. They all wear too many clothes, in Moomins' opinion.
The Hemulens have also featured prominently in other Moomin media, such as comics and animated TV series.