Leprechauns are a type of faery, and quite the most famous of those from Ireland.  

Contrary to how American's view Leprechauns, they are shoe-makes and dress quite ordinary according to Yeats.  Although they can be mischievous and play tricks on mortals, they would just as soon be left alone to their craft. 

Histories suggest Leprechauns favor red coats, not green, and the idea they have a pot of gold at the end of a rainbow is a singularly American creation.  They do have treasure though and the ability to trick mortals so as not to have it stolen from them.  

Although when we think of fairies in America a vision of Tinkerbell may come to mind, Irish Faerys are quite a bit different.

Fearys are the descendants of the Tuatha Dé Danann who were in turn the descendants of the Goddess Danu.  Some faerys live in groups while others are solitary.  They are inbetween spirit and physical.  ​Faerys are not  the benign helpful creatures of modern fairy tale. They are a group to themselves.  Some may be benevolent, others malevolent, or both depending upon the situation or the perciever.  Woe be to those that disrupt or destroy a faery fort or tree for they will find bad luck upon their heels.  This is not just a superstition, if you ask those that know.  Best be to simply leave them alone.