Jenna Marbles
Satan, according to Jacksfilms and all his viewers. even though the majority of YIAY fans might not have even seen a Jenna Marbles video in their lives.
YIAY viewer: *Sends Jack a picture of Jenna*
Jack: Oh, how did Satan get in here? No place for Jenna Marbles, right Klondike?
Klondike: *Confused, she just licks Jack's face hoping to make him happy even though not even dogs can heal souls as dead as his*