Isaac
RebirthUnlockedUnlocked from the start
How do you unlock Isaac?
Verified starting unlockSource data confirms that no unlock is required.
Isaac is the default starting character and is available from the very beginning of the game with no unlock required.
Available from the start
No unlock needed — this is available in every new save file.
Completion marks
Mom's Heart or It Lives!
Isaac
???
Satan
The Lamb
Mega Satan
Boss Rush
Hush
Ultra Greed
Delirium
Mother
The Beast
What unlocking Isaac leads to
Source: bindingofisaacrebirth.wiki.gg
Imported 2026-09-13
Available from the start.