Old-school magic meets the modern world when young Alex stumbles upon the mythical sword Excalibur. He soon unites his friends and enemies, and they become knights who join forces with the legendary wizard Merlin. Together, they must save mankind from the wicked enchantress Morgana and her army of supernatural warriors.
| Actor | Role |
|---|---|
 Louis Ashbourne SerkisAlexander "Alex" Elliot | Alexander "Alex" Elliot |
 Dean ChaumooBedders | Bedders |
 Tom TaylorLance | Lance |
 Rhianna DorrisKaye | Kaye |
 Denise GoughMrs. Elliot | Mrs. Elliot |
 Angus ImrieMerlin | Merlin |
 Patrick StewartOld Merlin | Old Merlin |
 Rebecca FergusonMorgana | Morgana |
 Genevieve O'ReillySophie | Sophie |
 Noma DumezweniMrs. Lee | Mrs. Lee |
 Nathan Stewart-JarrettMr. Kepler | Mr. Kepler |
 Mark BonnarMr. Jeffreys | Mr. Jeffreys |
 Alexandra RoachMs. Foster | Ms. Foster |
 Nick MohammedMr. Hyde | Mr. Hyde |
 Adam BuxtonStonehenge Tour Guide | Stonehenge Tour Guide |
 Claudie BlakleyRiding Instructor | Riding Instructor |
 Myra McFadyenPunto Patty | Punto Patty |
 Adam LeesePoliceman | Policeman |
 Joey AnsahPoliceman | Policeman |
 Amir WilsonBoy (uncredited) | Boy (uncredited) |
| SSean ColemanStudent Fighter | Student Fighter |