Acausality, also known as noncausality, causality immunity, and causality transcendence is defined as the ability to exist outside of causality, or the natural flow of events defined by cause and effect. An entity that is acausal has no true beginning or end, and is thus basically immune to offensive causality manipulation and time travel. Even if you go back in time and kill an acausal being in the past or prevent him/her/it from being born/created, it will still exist in the present and other timelines. Often, even if an acausal being is killed in the present it can still survive by appearing from another timeline. Thus, acausal beings are very difficult to permanently destroy, often requiring the use of high - level reality warping.

Examples of acausal beings in fiction:

- The Shrike from the Hyperion Cantos
- Hyper Kabuto from Kamen Rider Kabuto
- Most cosmic beings
- Guts from Berserk (he can still be killed but is just immune to certain forms of causality manipulation)
- Dispel Bound users from Bastard!!
- Daemons and Chaos Gods from Warhammer 40,000
- Gold Experience Requiem from Jojo's Bizarre Adventure
- Haruka Kaminogi from Noein
- Light Hawk Wing users from Tenchi Muyo!
- Sol Badguy from Guilty Gear
- Super Galaxy Gurren Lagann, Tengen Toppa Gurren Lagann, Simon, and the Anti-Spiral from TTGL