Luuke Skywalker was a clone of Luke Skywalker. This was years after the Clone Wars, so clones weren't quite the cheaper-by-the-dozen commodity they used to be. He was created by the crazy cloned JediJoruus C'baoth (who was a clone of Jorus C'baoth; he had a thing about adding U's to clones).
Luuke was none too bright. His brain hadn't really formed yet, and because he'd been cloned directly from Luke's severed hand from Cloud City, Luuke often suffered the delusion that he himself was a hand. One time Joruus C'baoth found him walking around covered in a huge Isotoner glove. Under the tutelage of his crazy master, Luke learned how to swing a lightsaber and to shout menacing things like "Me Luke Skywalker!" and "Me go to Tosche Station! Me get power converters!" and "Me bang Leia! Dat OK because me clone and not technically her brother."
Luuke's crowning moment of glory came when Mara Jade killed him, which kinda, sorta, not really fulfilled Emperor Palpatine's command that she KILL LUKE SKYWALKER. Luuke's final words were "Me not see dat plot twist coming."