It's called backtick.

If you program in a language which has had common use for back-ticks for a while, then yes, I'd prefer that term. The term "grave accent" is equally correct, though, and for more people. Being that my goal here is to introduce the character to people who don't know of its possible use within JavaScript, I chose to use the general term. In the opening sentence I introduce the character under both names to try to mitigate any confusion for those who have only known the character as a back-tick.