Hodor

Hodor is a character in Game of Thrones. He is played by Kristian Nairn and will first appear in the first season of the show.

Hodor is a stableboy serving at Winterfell. He is large and slow of wits, but is gentle and loyal to the Stark family.

In the books
In the Song of Ice and Fire novels Hodor is a descendant of Old Nan, the oldest woman in the castle. Hodor's real name is Walder, but he is only capable of speaking the word, "Hodor," and has become named for it. The meaning of the word is unknown.