There are many characters featuring in the Fusionfall film, including:

 

Main Characters: 

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Aelita Schaeffer (Code Lyoko)

Jeremy Belpois (Code Lyoko)

Odd Della Robbia (Code Lyoko)

Yumi Ishiyama (Code Lyoko)

William Dunbar (Code Lyoko)

Steven Universe (Steven Universe)

KO/TKO/PKO (OK KO: Let’s Be Heroes!)

Dendy (OK KO: Let’s Be Heroes!)

Ben 10 (Ben 10 Classic) *The Teenage One*

Eon (Ben 10 Classic) 

Mao Mao (Mao Mao: Heroes of Pure Heart)

Badgerclops (Mao Mao: Heroes of Pure Heart)

Adorabat (Mao Mao: Heroes of Pure Heart)

Rex Salazar (Generator Rex)

Franz Hopper (Code Lyoko)

Professor Paradox (Ben 10 Classic)