After being struck in the face with puck, Jacques Plante returned to the game sporting a protective face mask. NHL.com has great coverage in their NHL History section, including first hand accounts from Red Fisher.
It seems almost insane nowadays that goalies used to play without a mask on. But believe it or not there was quite a lot of pressure on Plante to not wear the mask. By pioneering the mask as the first goalie to regularly use one, Plante is forever immortalized as one of hockey's most important players.
By the way, it wasn't Plante who first wore protective facial equipment in NHL history. He was just the first to use it regularly.
This former Ottawa Senators goalie nicknamed Praying Bennie was the first NHL goalie to wear a mask, as primative as it may be. As you can tell in the photo in the link, that mask wouldn't do a whole lot of good in a modern era of slap shots, curved sticks and raised pucks!
Johnny Bower also experimented with a "windshield" mask. Check out the 5th photo down on his biography page.
The last goalie to play in the NHL without a mask? That would be this former Pittsburgh Penguins goalie.
And the father of the modern day NHL goalie mask - this man, who is better known as the brother of a true NHL goaltending legend.