I think if you look at it in the absolute simplest form of able to kill the average player, there are a ton of things that fall into the comparable power pool. Assassin, ranger, pretty much any warrior with a lagging spec, almost all Battle berserkers.

The thing about mummies, and necros in general, is they are more dangerous to lower skill players than to higher skill players. Sleep certainly comes closer to an "I win" button regardless of player skill but there are also a lot of crafty ways to mitigate it.