So my wife was watching "Castle" and it stars Nathan Fillion better known to me as Mal Reynolds from "Firefly".

When I saw him I said "Hey look, it's Mal" and all of a sudden she realised who he was (and that you couldn't take the sky from him).

She'd been watching "Castle" for 2 seasons and it never even twigged.

Have you ever been watching a show and just didn't realise a certain actor was playing a role, and once you realised just coudln't figure out how you missed it?

The trailer for Red Dawn (the new one)

Seeing Josh Peck, I was like "He looks like Josh from Drake&Josh..."

Lo' and behold it was! Well, 100 pounds later

I immediately recognized him.

It happens from time to time, I guess. Can't remember anyone in particular though.