Jacksepticeye

Seán William McLoughlin, aka Jacksepticeye, is an Irish YouTuber and Let's Player, best known for his eccentric personality and catchphrases. He is one of the most popular let's players on YouTube, with over 10 million subscribers.

Game Grumps
Jack has been mentioned by the Grumps on a few occasions, usually when also talking about the Grumps intern Jack, who is also Irish.

Jacksepticeye was a guest on Grumpcade, in which he played Shadows of the Damned with Arin and Barry.