First Edition
| Card Name | Number One |
| Type | Treasure Deck |
| Card Text | Monsters have -1 on your turn. Your attack rolls of 1 or 6 count as misses. |
| Category | Passive Items |
| Game Mode(s) | All Game Modes |
| Set | The Unboxing of Isaac  |
| Released | 2022 |
| Language(s) | English |
| Background Artist | Yazawa Akio |
| Card Artist | HamBerry |
Number One, along with Butt Penny! and Number Two, was exclusive to The Unboxing of Isaac subscription service for November 2022 (Binding Pale Kid Box).