Characters I've seen cosplay past me in the last 30 seconds:
1. Moogle; someone's toddler.
2. Professor Science. (Well, actually, it was just a T-shirt, but still.)
3. GODOT. With "Hold it!" sign in hand!

If I were only faster to react - ahh!

(I've been seeing the TF2 cast all day; at least 6 classes. Popular!)