Dr. Gregory House
Dr. Gregory House is a board certified diagnostician with a double specialty of infectious disease and nephrology. The guy is a really, really good doctor.
He cares far more about solving cases, which he sees as elaborate puzzles, than about the patients themselves. House is a grumpy individual, largely due to the blood clot in his leg that leaves the character with a perpetual limp.
He's been hooked on Vicodin, and on being an ass to those around him. But we still can't get enough of the guy!