The Hemulens are a species in Tove Jansson's Moomin stories. They are large humanoid creatures looking something like thin hippos, generally wearing a long dress-like tunic or robe.
Hemulens are a bit under-defined -- probably intentionally -- but there are a few well known Hemulens, all named Hemulen, The Hemulen, or Mr. Hemulen (they are almost all male). They are often obsessive and hyper-focused, ignoring major events in favor of winter sports, collecting butterflies or stamps, stargazing or building. However, we also see examples of Hemulen who are lost and without purpose, notably in Moominvalley in November and Tales From Moominvalley. While Hemulens are usually solitary creatures, they do have families and some families are quite convivial.
The average Hemulen in the street will be brusk but not hostile, and more than willing to share their interests, although you should not expect any reciprocity. They will generally ignore your problems and views, overwriting them with their own, and ignore social niceties. However, if sharing their interests can help you, they will happily do so.
When we English-speakers try to refer to Hemulen, we get all mixed up. In Swedish they are Hemul; to say 'the Hemul', the Swedish language adds an -en, that is, 'Hemulen'. In English, -en sounds like an acceptable plural form (cf. children and oxen). The upshot of this is that the English plural of Hemulen can be Hemulen or Hemulens, and that we sound dumb to Swedish speakers.
It is worth noting that in Old Swedish Hemul means 'rightful' or 'proper'.