Game of Thrones is a new medieval fantasy series on HBO, which is based on the book series A Song of Ice and Fire by George R.R. Martin.
[youtube]http://www.youtube.com/watch?v=8ixEWrTLiZg[/youtube]
The show started a few weeks ago and it's really good (same goes for the books), so here's the synopsys of Wikipedia:
Set in the Seven Kingdoms of Westeros, where "summers span decades and winters can last a lifetime," Game of Thrones chronicles the violent dynastic struggles among the kingdom's seven noble families for control of the Iron Throne; as the series opens, additional threats from the snow and ice covered region north of Westeros and from the eastern continent across a narrow sea are simultaneously beginning to rise.
Everybody who likes dark and gritty fantasy should give it a try.