Here's a nice list of some from an old thread... Some are TV shows... others don't exactly fit "medieval" genre but they are close to it. They vary in quality.
http://forum.melee.org/general-off-topic/thread-of-medieval-movies-and-tv-shows/1612
300
13th warrior
Agora
Alatriste
Alexander
Arn knight templar
Arthur
Berserk: golden age
Black Death
Borgia
Braveheart
Centurion
Deluge
The Eagle
Excalibur
First Knight
Flesh and Blood
Gladiator
Game of Thrones
Ironclad
Il Mestier Delle Armi (The Profession of Arms)
Joan of Arc
Kingdom of heaven
Knights of the Teutonic Order (Krzyżacy) 1960
Knight's Tale
The Last Legion
Lion in the Winter
Mongol: The Rise of Ghengis Khan
Monty Python & the Holy Grail
Old Fairy Tale: When the Sun Was God
Outlander
Pathfinder
The Pillars of the Earth
Robin Hood: prince of thieves
Robin Hood (2010)
Reclaiming the blade
Seventh Seal
Spartacus: blood and sand
Tudor
Troy
Vikings
White Queen
With Fire and Sword
I really liked The Eagle... Kingdom of Heaven is a definite must see... Alexander was awesome as well, if that's the one I'm thinking of with the war elephants scene...