A question arising from a recent thread about the murder spree of Malekith the Accursed. This is not a uniquely Marvel phenomenon, but I did start wondering.
These below are the ones I can easily recall - please feel free to add but also to correct my faulty math
Civil War #1 - 200 school kids blown up
The Siege - Norman Osborne blows up a sports stadium with about 20,000 people in it.
Avengers - Perth gets hit by an alien plague meteor - population of about 2 million
Avengers - Kang blasts Washington with Damocles base and vaporizes population - up to 5.9 million people.
Others?