Cheap boss fight? Most of the Souls games come to mind, as well as most fighting games. Shao Khan, Akuma, Seth, Uriel, Marie, Azazel, Unknown, Dizzy, and the magneto thing in the original Marvel vs Capcom.
Virgil in DMC3. Or the Nirvana in DMC 3. They did some really cheap things.
A lot of JRPGs had quite a few cheap boss fights as well, *looks at dragon quest, Shin Megami Tensei, and Earthbound*
Now you excuse me, I have some Bloodborne bosses to rage at