McGregor reached the summit of the 155lbs division in the main event of UFC 205, a card which saw him create history by becoming the first UFC fighter to hold two titles simultaneously.
The Irishman has yet to defend the title he claimed with a vicious second-round TKO victory over Eddie Alvarez, much to the frustration of many in the division.
The birth of his first child, Conor Jr, and a multi-million-pound boxing match with Floyd Mayweather Jr played key roles in McGregor's hiatus from the Octagon and the lightweight division grinding to a halt.
An interim 155lbs title was brought into the mix to keep the weight class moving along and was claimed by Tony Ferguson in the main event of UFC 216 in October.