Which UFC event featured Jose Aldo vs. Conor McGregor?

José Aldo vs. Conor McGregor took place at UFC 194. The event was held on December 12, 2015, at the MGM Grand Garden Arena in Las Vegas, Nevada.

The bout was a UFC featherweight championship unification fight. Aldo was the established champion, while McGregor entered as interim champion after Aldo had withdrawn from their originally scheduled UFC 189 meeting because of a rib injury. Chad Mendes replaced Aldo at UFC 189, and McGregor won the interim belt.

At UFC 194, McGregor stopped Aldo with a left hand just 13 seconds into the first round. It was one of the most spectacular finishes in UFC history and, at the time, the fastest knockout in a UFC title fight. The result unified the featherweight championship and made McGregor the undisputed champion.

UFC 189 is a common mix-up because it was the original date for Aldo and McGregor. UFC 196 was McGregor’s later fight with Nate Diaz, and UFC 205 was the event where McGregor won the lightweight title from Eddie Alvarez. None of those events hosted the Aldo-McGregor fight.