June 16, 2011
Since then, one of those channels hit 3 million, and several others crossed joined that original 15 bringing the "million+ subscriber club" to a total of 35 channels.
Many of these channels accomplished the milestone in just the past few weeks. Tobuscus, Kurt Hugo Schneider, Rooster Teeth, Venetian Princess, and Epic Mealtime all recently crossed the 1 million subscriber mark.
The most recent to cross the threshold is the UK's Charlie McDonnell, who posted this this commemorative video on his channel, charlieisocoollike.
Who Will Be Next? communitychannel, Selena Gomez, and The Gregory Brothers are all very close to earning membership.
(Updated to reflect that Rooster Teeth hit 1 million shortly after posting.)