One Perfect Moment: John the Skrull
Well, the Captain Britain and MI:13 bit that ran as part of Secret Invasion is proving pretty damn popular for One Perfect Moments, and here I come with another one. Spoilery as hell, from issue #4
I'm not sure how many people could have their death be the one defining moment, but for John, and in both my opinion and that of his teammates, the way he went out was a complete encapsulation of who he was, both the Skrull himself and the Beatle he'd spent decades being.
I also thought the fact that he remained human even in death (in an earlier page, you can see that only the place where he was shot reverted back to Skrull shape, the way all of him was biologically supposed to) was a nice visual touch to compliment his mindset.