Seán was on YouTube for a year before he won a contest by fellow YouTuber, Pewdiepie, in 2013. Pewdiepie mentioned him as the winner for the contest, and Seán become popular in mass.
Seán dyed his hair a vibrant green colour, alongside fellow YouTuber Markiplier (Mark Fischbach) in an event for charity.
Seán used to play drums in a band called "Raised to the Ground".
Seán began work on his YouTube Channel - Jacksepticeye - in 2012.
Seán actually joined YouTube on the 24th of February, 2007, but his first video was not uploaded until 12th November, 2012.