Who is Lost's Ethan Rom?

That question has Lost fans feeling a bit lost. We know that the creepy character, played by Tom Cruise's real-life cousin William Mapother, wasn't on the downed plane's original manifest. And we know that he wants Claire's unborn baby. But why? Mapother is sworn to secrecy. All the show's producers will tell us is that his name, Ethan Rom, is an anagram for "Other Man." Great, more mysteries! So until the show returns Jan. 5 on ABC, here are the Top Four theories on just who the slimy fellow might be.

1. Ethan is the devil.
If you subscribe to the "they are in purgatory" theory, then he is coming to claim the already dead child's soul.

2. Ethan is an evil alien shape-shifter.
First, he took the form of the raging polar bear. Now he's human and, for some strange reason, he must destroy the baby and keep anything good from prospering on the island.

3. Ethan is Alex, Danielle Rousseau's lost son.
He knows something's not right with the island and wants to take Claire's baby to protect — or destroy? — it.

4. Ethan is a member of Danielle's fallen science team who has gone mad from the "whispers."
He stole Alex from Danielle and is now trying to take Claire's unborn child. One good child, one evil. Rosemary's Baby, anyone?