The Kodiak or Alaskan Big Brown Bear would be the largest of the bears.

 

Oh

 

As I was scrolling through this thread I was going to say the very same thing, until I saw you had already said it.
When I was in Alaska I saw several bears, but I did not get the pleasure of seeing a Kodiak (maybe that is a good thing)!
The scary part is (I don't know how true this is) but I heard that after a bear's heart has stopped beating he/she can still charge 100 yards and have enough adrenaline left to kill you!