The Greek Gift Sacrifice
One of the thematic sacrifices in chess is called the Greek Gift. This refers to a bishop sacrifice on h7 (or h2 for black) followed by a Ng5+ and bringing the queen to the kingside for a mating attack. Even when the sacrifice is not perfectly sound it is tricky to refute, here are a couple examples from my games at chess.com
In the first game, black finds himself with no pieces on the kingside. After the sacrifice, black can manage a draw by bringing his king into the open with 12. ... Kg6 (see move list), but loses with 12. ... Kg8.
In the second game black will again miss a complicated draw and succumb to an overwhelming attack.
In both of these games, the Greek Gift wasn't actually winning, but lead to draws with correct play from black. However, the strong attack allowed black enough opportunity to make a mistake. Don't be fooled sometimes the Greek Gift is actually winning :-).
More Greek Gift resources:
A collection of games at chessgames.com (lots of examples here)