The Headmistress

The Headmistress, also known as The Host (not to be confused with hosts in general), is the host of Murder-Free and Murder U.

Backstory
Prior to Murder-Free, she participated in a murdergame run by Timeline Master Awe and was killed. Due to unstated "incredibly precise circumstances", she awoke from her death with god-like control over a personal pocket dimension.

Murder-Free
With her newfound god-like powers, she opted to create the Murder-Free Hotel and summon the players of some recently-completed murdergames, starting with Sylvi Elakha, Stew, Pizzacatcher Cutbug, Rebel Cookie, Avery, and many others.

Murder U
After running Murder-Free for some time, she decided to create a murdergame of her own.