|Base Health:||3 hearts|
|Starting Pickup Items:||1 Bomb|
|Starting Activated and/or Collectable Items:||N/A (until the D6 is unlocked)|
Isaac is the titular character in The Binding of Isaac and The Binding Of Isaac: Rebirth, and the first available character in both. He is also the only character who does not need to be unlocked.
Isaac's stats are simple, and he is considered the base of all characters.
Isaac starts with no activated item, but after beating The Womb with ???, Isaac gains The Dice.
In the Cathedral, Isaac also appears as the main boss.
- Isaac, as well as the game itself, are named after the Old Testament account of "The Binding of Isaac", with which they not only share the name but also the basic story, in which God asked Abraham to sacrifice his son Isaac to Him.
- Edmund McMillen refers to Isaac as the "fighter" character, with increased health and average stats.
- The name "Isaac" means "laughter" in the Hebrew language. This is ironic due to Isaac constantly crying.
- Edmund has stated that Isaac is left-handed.
- Isaac is bald because his mother shaved his head.