Here are my picks for the top five most iconic covers featuring Iron Man (with iconic being determined by what covers are most established and most recognized when it comes to Iron Man, with a preference towards covers that are homaged a lot). This is not a BEST cover list and due to the very nature of icons, very few (if any) recent covers will be on the list. A notable exception to the rules is that I don't count covers from a character's first appearance (which isn't applicable to all characters, of course, just those who appeared on the cover of the comic they debuted in), as those tend to be automatically iconic so they're boring. Here's a list of all characters featured so far.
Enjoy!
Before the list begins, here is the first cover appearance of Iron Man, from his debut issue...
Artists: Jack Kirby and Don Heck
Now on to the list...
HONORABLE MENTION
Artists: Gene Colan and Mike Esposito
Colan's cover for the first issue of Iron Man set a tone for a lot of Iron Man covers to follow, including an artist later on this list who managed to create an even more iconic visual while basically following Colan's general template.
5. Artist: Bob Layton
Bob Layton is a very popular artist to commission cover recreations from, especially Iron Man covers. This cover is the #1 most requested cover recreation he gets.
4. Artists: Luke McDonnell and Steve Mitchell
I debated between this one and the previous issue's cover ("YOU be Iron Man!").
3. Artists: Gil Kane and Vince Colletta
While following the basic foundation of Gene Colan's #1 cover, Gil Kane produced a much more iconic vision of the Power of Iron Man, creating an image that would be followed by later artists frequently (including Jim Starlin on the cover of Iron Man #100, who pretty much did a straight homage of this issue's cover, which is why that great cover is not on the list).
2. Artist: Adi Granov
This is the rare example of a modern cover becoming an iconic cover. This image was huge and even ended up in the Iron Man movie!
1. Artist: Bob Layton
Demon in the Bottle is simply the most famous Iron Man story, and this cover is the most iconic aspect of that storyline (much more so than any interior image from the story).