If you're not watching Nathan Fillion on 'Castle,' my Must List is superior to yours

I’m hopping on the Castle train. Make room!

I hadn’t been avoiding it on purpose; it just fell through the TV cracks. For that, I’m slightly ashamed. Thankfully, I don’t think I’m the only one late to the party. The last new episode attracted more than 10 million viewers, a commendable increase from the last few recent episodes. The cause? Not sure. But my non-scientific answer is Nathan Fillion.

”But Sandra,” you say, ”he’s been on Castle since the beginning.” Right you are, and we’ve always loved him here on PopWatch. But quite honestly, I’m experiencing a Nathan Fillion revival. Gone are the days I TV crushed on Johnny Donnelly (Fillion’s character on Two Guys a Girl and a Pizza Place), and I just stopped scribbling ”I <3 Captain Hammer'' in my spiral notebook at EW.com meetings. Now, it's all about Richard Castle. Fillion's portrayal of a famous mystery novelist-turned-crime-solver is equal parts humor, adorable and charm. And my reaction is all parts love. It also helps that Fillion's Twitter (@NathanFillion) keeps me entertained in between new episodes (as do Ausiello SPOILERS).

I have a long weekend of marathon-ing ahead of me before the new episode on Monday (check out a preview below), but in the meantime, tell me which underappreciated star is on your Must List this week. Is someone killing it on TV without proper kudos? What other books/movies/web sites are you loving?