The 90-second trail features new footage from the fantasy drama's latest episodes, expected to air in late 2012.
The legendary round table of Camelot, the Great Dragon (voiced by John Hurt) and guest star Liam Cunningham all appear in the new footage.
Digital Spy also has an exclusive first look image of Morgana (Katie McGrath) in series five:
McGrath recently suggested that the fifth series of Merlin will have a more adult feel.
"It's a three-year time-jump, so... we're all older," she explained. "We were playing... very early 20s at the start, now I feel like we've all started to play adults, which for us is a great change."
Guest stars confirmed for the new series include Lindsay Duncan (Doctor Who), Janet Montgomery (Entourage) and John Bradley (Game of Thrones).
> Merlin series five trailer released by BBC - watch
> Merlin series five, film trilogy teased, new image released