While my mind is still on the printing process, and to follow up on a post I did a while back, I'm going to show some example of what I think is a true four-colour hero.
Doctor Fate is one of my favourite DC heroes, and I like him because technically, Doctor Fate is the printing process. Observe:

Tatjana Wood is the colourist for these pages, and I think she's one of the best. Her work on 'Swamp Thing' is incredible and she has a true mastery over mixing inks and knowing when to let them stand on their own for impact. Check this panel out:

And just to bring it home, this incredible panel which, as above could almost be a spot-job.

The four-colour process is essentially four spot inks screened together to give the illusion of colour, but I love in these examples how they are used as the colours they are unmixed, and either at 100% or screened back a little.
[Art by Keith Giffen and Larry Mahstedt, 1985]