Skewer
What is this tactic called?

It's called a "Pin". When a piece is "Pinned" against the King I think it is also referred to as an "absolute pin" - as it's illegal to move the "pinned" piece.

@Benkobaby - Thanks for info. I'm suprised there's not a special case (term) for a pinned queen.
@KyleMayhugh - Skewer, or X-ray attack, is something different. Where the attacked peice is on the otherside of the king, for example, if the positions of the black K & Q were reversed (see below), this would be an X-ray.

Chess.com has a page that goes over various tactics.
http://www.chess.com/article/view/chess-tactics--definitions-and-examples
Is there a term for the tactic of attacking a peice and your opponent cannot move to avoid the attack without putting himself in check?
This comes up a lot in games and is usually a devastating move when the attacked peice is a queen. Sample board below.
Thanks in advance for the info!