But, surprisingly, the Mighty Mite did face off against a few legions of undead during his days in comics!
Back To the 1960s
It was really aliens called the Physalians who were possessing human hosts to take over nuclear power plants to harvest their energy.
In his alter ego, the mighty physicist Ray Palmer, along with frogman Jonah Waite, were able to work together to stop the aliens and turn off the nuclear reactors, preventing the aliens from feeding on the energy, putting an end to Atom's solo adventures in a book of his own for a time.
Closer To The Modern Age
But even through all of that, the pair remained friends....
Atom and Hawkman reunited during the course of the Blackest Night event (where legions of DC heroes and villains returned from the dead thanks to the efforts of a Green Lantern Corps villain in 2009/2010) over the course of 9 issues for the main event, along with many, many crossovers....
...including one special one....
Not bad for a scientist only six inches tall, right, to take out all of the undead?