Matt nailed down the answer but here are a couple more thoughts.

All artists swipe, in the traditional sense it's called  "a study". So one might do a study of a Frazetta piece, trying to get it as close as possible to the original. As long as they don't try to make a profit off that study, then no harm no foul. It's in the spirit of learning.

Many artists actually don't know the difference between swiping and using reference. If you are using the same composition of an existing piece, it's a swipe, clear and simple. Doesn't matter if it's existing art or a photograph. 

I've read an article years ago where the artist claimed to use "photo reference" but clearly swiped (and perhaps traced) the composition of a bikini model's photo and put clothes on her. He swiped the composition the photographer had created.

If you are tracing, it's worse than a swipe, it's out-right stealing. A couple (well....at least one) artists trace images. I can't believe there hasn't been more lawsuits regarding this.

There was a contest years ago held by a company who sells a vector art program. The contest winner traced a photo of an indian head and presented that as his original work. He thought it was ok to trace the image, using it "as photo reference" because his art style was vector based gradients and not photographic. Nope, he was sued and lost.

So from what I can gather, here is the barometer as I see it:

1. Original. you have created a piece that comes entirely from your imagination and/or experience.

2. Inspiration: You use a previously published idea but your composition is clearly different. Thats ok because there are only so many ways you can draw 2 teams facing off, for example.

3. Reference. You borrow small elements from multiple sources to create a composition that is clearly original (is it really though?) and none of the elements are easily identifiable coming from your source material. 

4. Homage. You have clearly swiped the composition of an existing piece but are very public about it, hopefully giving credit where credit is due for your source material. As long as this is done respectfully it seems to be ok in the industry.

5. Swipe. You have clearly taken the composition from an existing piece and it is clearly obvious, and most likely you are not giving credit to your source material. Doing so after-the-fact doesn't make it an homage. As JB has stated, there is no such thing as swiping your own art.

6. Tracing. Just wrong. Don't ever trace another artist's work for your own profit and gain. You should get sued.

7. Fraud. Presenting another artist's work as your own. Go straight to jail.

What are your thoughts? Are there any steps that I've missed?

All I can think of when I see this early version of Hyperion is "Super Diaper-Man".

Getting back to the topic of swipes, in his book The Great Comic Book Heroes, Jules Feiffer praises the art of the swipe during the Golden Age, particularly in the work of Sheldon Moldoff on Hawkman where he swiped Alex Raymond on a regular basis. Swiping was simply considered a part of the job, a way of making sure you're solving the story telling problems in the very best way you can, creating the best results. If someone else has already done what you need done, you'd simply incorporate that into your work and move on. Moldoff has said in interviews that he doesn't know of any artist who doesn't keep a "morgue file" of other artists' work and cites advertising artist Albert Dorne as someone who routinely relied upon swipes. Fieffer rhapsodizes a bit about how he enjoyed "catching" Moldoff at it, being very familiar with Raymond's "Flash Gordon" himself. 

I'm not a fan of swipes myself and still nurse a grudge against Keith Giffen and his Ambush Bug swipes, moreso for the defense he offered when caught drawing line for line from Spanish artist Sampayo. He claimed at the time to have done so unconsciously, having been so powerfully affected by Sampayo's work that he didn't quite realize he was doing it... Line for line for page after page... Ye-ahh... Sure. 

But it is interesting to see them regarded here and there as a tradition, even a proud one, and an open secret in the industry.

With others, I feel it's quality, but not quantity. You could make 50 live-action Batman episodes and there's a chance 80% of the episodes would feature good, strong opponents; but with some superheroes, you'd run out of first-rate opponents fairly quickly. 

I could be wrong, just how I feel.

Does IronMan have an arch nemesis? Tony Stark had a couple - Stane and Hammer, but Iron Man? Only the Mandarin comes close.

I'm curious what others think?

Black Widow (reformed)

Titanium Man

Crimson Dynamo

Mandarin

Ultimo

Jack Frost/Blizzard

Whiplash/Blacklash

Ghost

Living Laser

Madame Masque

Spymaster

Controller

Black Knight (dead)

Iron Monger (dead)

Melter (dead)

The Mandarin in clearly the cream of the crop.