Theory-Light Gets Reincarnated As A Shinigami

In Death Note: Relight, an unnamed Shinigami appears. Many fans believe this Death God is Light reincarnated. Plenty of evidence exists to support this theory. For one thing, the Shinigami wears a blood-stained coat resembling the one Light dies in.

Additionally, his mouth and voice appear similar to Light's. He knows about Ryuk's unusual affinity for apples, even throwing one to Ryuk the way Light did in the past. There are continuity issues between the original Death Note and Relight, so it's possible this Shinigami is meant to be Light, even though the original series states nothing happens after death