A question that comes up from time to time concerns to old tale that your hair and fingernails (and toenails, but who would notice) continue to grow after death and burial. This is likewise at times portrayed as happening on TV and in movies. Sorry, but they don’t. Although, folks arising from the grave do look better with them long and menacing or straggly.
Hair and nails are skin accessories, not decorations, but accessories in that they grow as a part of your skin. As is true with everything in the body, continued growth requires continued metabolism to fuel that growth and continued circulation to supply nutrients to feed the ongoing metabolism. Of course both circulation and metabolism cease with death. No metabolism, no circulation, no continued growth.
Nonetheless, nails and hair can at times seem to the eye to have continued to grow after death. If the body undergoes dry decomposition, also known as desiccation or mummification, the body shrinks in size drawing the skin toward the bones. That natural process can in turn make the hair and nails appear to be longer in relation to the shriveled body. That is likely where the tale began.
So the Crypt Keeper, if he is truly dead, would not look quite as eery. But reality is not always what it is cracked up to be.