The Lost

The Lost is a playable character in The Binding of Isaac: Four Souls. Unlike all other characters, he only has 1 Hit Point and also starts out with 1 Soul.

Strategies
The lost starts out with a soul, so you only need to kill 3 soul-bearing enemies or find the 3 soul cards to win

Holy Mantle is a good item since it can prevent you from dying when you take a hit.

Additional notes

 * The Lost is an exclusive character in the Gold Box tier, which you could only get during the Kickstarter.