No Hicks? 
I would have assumed an Atlas poster might have included Coase or Arrow or someone but you've clearly taken a classic internet libertarian route in making this list.
Yeah, Hayek was not an actual economist. Political theorist/philosopher is a more accurate description.
Pretty sure Ricardo deserves a spot in the top 10.
Hayek is a respected figure in the economics profession. Von Mises, of those on this list, would be more of a problem. Along with Marx, he shares the dubious distinction of starting a religious cult. But, at least, Marxism has been influential.
Hayek was absolutely an "actual" economist. It's not (entirely!) his fault he's been attached to a bizarre ideological movement based around some of his more archaic ideas.
Problem with Coase is that his theorem, while elegant in the hyper-simplified Flatland of Micro 101, has zero application in the real world due to transaction costs and power differentials mucking things up. And yet, plenty of folks (especially those conveniently on the "right" side of those differentials) will use it as an excuse to avoid being held accountable for their actions. So he's had a pretty pernicious effect all in all.
As for Hayek, I'm sure you've seen that quote of his where he basically advocates for a command-and-control approach to fighting pollution; I can't be too harsh on him knowing that (and, also, knowing that his real target was Stalinism rather than western-style social democracy). Though using that line to defend Hayek is kinda like saying "Nixon signed the EPA into law!", so take as you will.
...
Pigou, of course, is the best.
