Gioachino Greco was an early 18th century Italian player who catalogued mating patterns among other things. This one bears his name. There's nothing remotely tricky about a mate in one, but remember it's the pattern that's important. The theme of this mate arises frequently.
Below is an example of the Greco in action in a game situation from the website of Joh Edwards.
1.Ng6+ hxg6 2.Qh3#