Answer
Conor McGregor became the UFC Interim Lightweight Champion in 2013. This was after he defeated Chad Mendes by TKO in the second round at UFC 189. This victory earned McGregor the interim title, as the original champion, Rafael dos Anjos, was injured and unable to compete. McGregor would go on to defend his title against Jose Aldo at UFC 194, where he won by TKO in the first round.