Xor was a minor villain in, Star Wars: Knights of the Old Republic. He is a Twi'lek (or Human) Mandalorian who despises the Cathar species, the same species that Juhani, a Jedi companion of Revan, is a part of.
At some point, the Mandalorians under Cassus Fett invaded Cathar, a planet with a race of feline-like people. Xor hated the Cathar, viewing them as savage beasts. He enjoyed killing them. While most Mandalorians fought for the glory of battle, Xor fought simply for the pleasure of killing them. During the battle, Xor suffered injuries that prevented him from fighting.
20 years later, during the Mandalorian Wars, the Mandalorians invaded Taris, which Xor also took a part in. After the invasion, Xor killed a Cathar male. He then attempted to kill his wife and daughter, Juhani, but they escaped. Two years later, Xor found Juhani on the auction block and tried to buy her. But then the Jedi under Revan liberated Taris and freed the Cathar.
Many years later, Xor, by chance, saw Juhani again on Manaan. This time, she was a Jedi accompanying Revan, now a redeemed Jedi searching for the Star Forge. He attempted to buy Juhani from Revan, but he refused. Xor claimed that the Jedi must hate nonhumans, even though he was wrong. He then brought up Taris, which angered Juhani. She wanted to kill him, but she remembered the Jedi Code and calmed down. Xor then left, swearing that he would get her eventually.
He then appeared near Revan's ship, the Ebon Hawk, with two thugs. He attempted to defeat Revan and Juhani, but failed. As he was dying, he boasted about what he did to the Cathar. He tried to goad Juhani into striking him down, and was nearly close, but Revan calmed her. She stayed her hand, and Xor died in disgust.