Eternal sleepers
When Egypt believed that mummies could come back, they didn't think that was because it was a dried corpse, they thought that because it was a well-preserved corpse.
The same belief that allows mummified bodies to get back up allows other well preserved corpses to get back up, including embalmed corpses.
Eternal sleepers are what happens when someone is embalmed well enough that it looks like they could just get back up, even several hundred years down the line.
And sometimes, they do.
Named for the fact that coroners put spiked contacts on the eyes of bodies, so their eyelids don't slip open during an open casket funeral. When an eternal sleeper gets up, they usually still have these contacts keeping their eyes shut, hence the name.
The most notable example of one is Abraham Lincoln, former president of the United States. Known for his role in the American Civil War.