Series 5

Series 5 will be the fifth series of the highly popular drama show, Merlin. It has been officially commissioned by the BBC, due to popularity and anticipation. This was confirmed 24 July 2011 by Julian Murphy and Johnny Capps. Filming will begin March 2012 in Cardiff, Wales and Pierrefonds, France. 13 episodes have been ordered.

However, at this stage it's not clear when the 5th series will be shown as Doctor Who seemingly will take the Autumn/Winter slot for its 7th series in 2012.

Confirmed Information

 * According to Julian Murphy in a recent interview, Merlin Series 5 will begin following a cliffhanger at the end of the finale of Series 4 (more of a cliffhanger than ever done before) which will become a large part of Series 5. This will involve the return of an evil character that we've met in earlier series. Whether this character will appear at the end of Series 4 and at the beginning of Series 5, or just in Series 5 is unknown.


 * Series 5 will open with a two-parter, just like Series 3 and Series 4 did.


 * There will be two new monsters or creatures that we haven't met before in the first couple of episodes.


 * There will be two dragons- Kilgharrah and Aithusa.

Source
Merlin season 5 secrets (Interview with Johnny Capps and Julian Murphy)

Cast

 * Merlin - Colin Morgan
 * King Arthur Pendragon - Bradley James
 * Guinevere - Angel Coulby
 * Gaius - Richard Wilson
 * Morgana Pendragon - Katie McGrath
 * Kilgharrah - John Hurt
 * Aithusa - ???
 * Sir Leon - Rupert Young
 * Sir Percival - Tom Hopper
 * Sir Gwaine - Eoin Macken
 * Sir Elyan - Adetomiwa Edun

Possible Cast

 * Freya - Laura Donnelly (very likely )
 * Alvarr - Joseph Mawle (very unlikely)
 * Uther Pendragon - Anthony Head (likely )
 * Agravaine de Bois - Nathaniel Parker (no information yet)
 * Mordred - Asa Butterfield (almost certain, since he plays an important role in the legend)
 * Sir Lancelot - Santiago Cabrera (possible, but still unlikely, since he is dead!)
 * Alator of the Catha - Gary Lewis (unlikely)
 * Alice - Pauline Collins (highly unlikely)
 * Isolde - Miranda Raison (no information yet)
 * Tristan - Ben Daniels (no information yet)
 * Queen Annis - Lynsday Duncan (Likely)
 * Hunthi - Caroline Faber (Likely)