Canis Majoris is not a star, it's a constellation... but there is a certain star in that constellation, namely VY Canis Majoris, which is a viable supernova candidate.
Other notable ones include Betelgeuze aka. Alpha Orionis (huzzah for northern hemisphere), Eta Carinae (southern hemisphere exclusive), Spica (Alpha Virginis) and Antares (Alpha Scorpii). There are others as well, but AFAIK these all belong to brightest visible stars available. Can't remember others without resorting to wiki, and I can't bother right now.
Mmm... daytime visible supernova... One that makes shadows at night. I once was lucky enough to be outside on
very clear winter night with new moon, so the sky was almost completely black. And lo behold, you could actually see Venus making shadows on the forest... It was somewhat unreal experience.
Would be kinda awesome to be outside late at evening, with clear sky, then suddenly one of the stars goes like *fwoommm*. What else could you possibly think than "holy shizzle..."
