Browsing the internet recently I saw an artistic rendition of the silhouette of Spike from Cowboy Bebop.
Suddenly a realization came crashing home -- the most memorable game / comic characters I can think of are all recognizable by their outline alone!
Feeling like I had stumbled across a secret, I shared my observation with my wife who informed me this is very common knowledge amongst designers. I likely could have picked it up by reading any guide on character design...
That said, the things you discover yourself always stick the longest -- I'll be keeping this in mind from now on while doodling characters for my ideas!