The Incumbent: James Spader, Boston Legal
Who Should Win: Hall should win for Dexter. Not only has he turned in an exquisite, fascinating and textured performance as Dexter Morgan (the main character of one of the most thrilling, fascinating series to air in a long time), but he's been due since season one. This is Hall's first nomination for Dex; he was nominated for his work as David Fisher in Six Feet Under back in 2002.
Who Will Win: Spader has been nominated for this part three times before—once while Alan Shore was still a character on The Practice, and twice for Boston Legal. He won all three times he was nominated, and there is absolutely no reason to believe his streak won't continue. Mad Men's Hamm, who won the Golden Globe this year for Best Actor, can be considered the most likely dark horse.