|Original broadcast||January 26, 2013|
|Series||Ben 10: Omniverse|
|Episode number in production order||23|
|Overall episode number||169|
|Written by||Matt Wayne|
|Directed by||Jae Hong Kim|
|Previous episode||Ben Again|
|Next episode||Special Delivery|
Alien 23 is the twenty-third episode of Ben 10: Aliens Unleashed.
- Spikesnake makes his debut by 16 year old Ben.
- Perk Upchuck, XLR8, and Bullfrag make their Aliens Unleashed debut.
- Ben 23 aliens JellOgre (Goop), Fishlegs (Walkatrout), and Rollspit (Ball Weevil) make their debut.
- Ben Tennyson (Dimension 23) (first re-appearance)
- Azmuth (Dimension 23) (first re-appearance)
- Tetrax Shard (Dimension 23) (first re-appearance)
- Sixsix (Dimension 23) (first appearance)
- Sevenseven (Dimension 23) (first re-appearance)
- Big Chill
- Perk Upchuck (first re-appearance)
- XLR8 (first re-appearance)
- Echo Echo (first re-appearance)
- Bullfrag (first re-appearance, cameo)
By Ben 23Edit
- Build-A-Guy (alternate version of Bloxx; first appearance)
- Smarty (alternate version of Grey Matter; first appearance)
- Darksoldier (alternate version of Night Knight; first appearance)
- Giant-Manster (alternate version of Way Big; first appearance)
- Feedback (alternate version of Feedback, first actual appearance)
- Freezelizard (alternate version of Articguana; first re-appearance)
- Alien 23 (alternate version of Alien X; first appearance)
- It is the Twenty-third episode of Aliens Unleashed because of Ben 23.
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