I'm not really into putting on costumes, but I appreciate that this is the time of year when you're supposed to do it. That's why I went to a Halloween party a couple of years ago wearing a custom-made t-shirt that said: "This is my costume." If you're a tee-loving dork like me, there are actually better options that that. Here are just a few.

Of course, the easiest t-shirt costume of all is to go as Roy from The IT Crowd (above), whose geeky t-shirts are the stuff of television legend. (Seriously, Sheldon's tees on Big Bang Theory are nothing compared to Roy's.) You can get his nice Flash t-shirt on Zazzle for $23.60 (though not in the same color), or read through the meticulous guide to finding some of his other classic tees (such as the "Meh." one) on Hide Your Arms.

(Some of these tees spotted on Hide Your Arms and Fashionably Geek)

Darth Vader t-shirt ($30 at 80s Tees)

A lovely selection of Star Wars hoodies, on sale for $34.99 at ThinkGeek

Yes, it's obvious, but you have to admit it's the ultimate t-shirt costume. A simple Star Trek uniform in red. Why were engineering crew always the ones to die? If you prefer not to meet the fate of the proverbial Red Shirt, you can always pick up blue or yellow. (All colors are $19.99 at Superhero Stuff)

There are many lovely chestburster t-shirts, but I like this one especially because it reminds me of the art on the outside of a van. ($24 from CafePress)

How about an old school Optimus Prime, just to show your loyalty to the pre-Michael Bay times? ($20 at 80s Tees)

Celebrate Matt Smith's Doctor with this hoodie that gives a reasonable facsimile of his trademark tweeds and bow tie. ($33 at Etsy)

Spider-Man Hoodie. You don't need anything else. ($60 at 80s tees)

Superman caped tee — I love the idea of a tee with a cape. There are also versions for Batman and Robin, too. ($30 at 80s Tees)

With this Captain Hammer tee, you can spend the evening reciting this lame good guy's immortal line: "The hammer is my penis." ($25 in the Dr. Horrible store)

Screw Green Lantern — you can be the Green Ranger! ($18.99 at Crazy Dog)

Or just become a generic teenage mutant ninja turtle. ($34.99 at 80s Tees)