Ok mine was really a no brainer for me. As I have most of this character's primary appearances raw already. Unlike Thanos, whom a few of us boardies, @djpinkpanther67 as an example, are collecting each one and have catalogued each one meticulously. I have not spent the time researching this character, maybe I should?
Back in my teenage years I went to a LCS, it is still there and has 3 locations in the Hampton Roads area of Virginia called Jersey’s Cards and Comics. I spent many a day and night there gaming and reading/talking about comics. I attribute much of the adult I became thanks to that shop and the owner, Bruce and his brother, Ray.
I would talk to them about books and what was a good read, this one week, Ray talked up a specific book and I ran with it. The #1 cover is a skull with a lenticular disk on it in the eye socket, which I thought was really cool, and the guy had a really different power, at least to me. The ability to die over and over but each time he came back from the dead he had a new power and never gets that power again. This could and did lead to some odd adventures for him.
The issue that really captured my attention was when he was forced to team up with a hitman in vol.1 issue #10. The hitman found out his power and proceeded to kill him over and over until he had something useful for the mission ahead of them. This was my 1st outing of collecting a full run. I am only missing a couple issues, mainly just never looked for them, I am sure I could find the 2 I am missing pretty easily.
So of by now you have not guessed, my uncommon character/series is Resurrection Man. His initial series ran for 27 reg issues and a spect 1 million issue with him coming back with New 52 running for a mere 13 issues.