27. "Under Siege" by Roger Stern, John Buscema and Tom Palmer (Avengers #270-277) – 381 points (1 first place votes)
This story was a brilliant example of sub-plots simmering to the point of boiling over in an explosive succession of issues. For a number of issues, Baron Zemo was secretly putting together a team of super-villains specifically designed to defeat the Avengers. Studying and planning, Zemo eventually put together such a large and powerful team of villains that his Masters of Evil were able to basically just bumrush the Avengers Mansion and take it over (taking advantage of another simmering sub-plot, Hercules’ distaste for being led by the Winsome Wasp – he did not like the idea of warriors like himself, Captain America and Black Knight taking orders from a woman). After beating Hercules within an inch of his life, they spent the next few days torturing their captive Avengers, including destroying all of Captain America’s belongings in front of him (including the only picture he had of his mother) and then making Captain America and Black Knight watch as they brutalized Jarvis, the Avengers’ faithful butler.
You have to love first how hardcore Cap is in the face of adversity (“I’ll remember this.” Chilling!) and then how disgusted Cap looks at Jarvis being attacked. Such amazing facial expressions from artists John Buscema and Tom Palmer.
This being the Avengers, though, they were able to make a comeback, with Wasp, the only Avenger to evade capture, putting together a makeshift team of heroes to save the captive Avengers (who were doing their best to free themselves). This likely remembered as writer Roger Stern’s masterpiece. And, of course, the aforementioned John Buscema and Tom Palmer did a wonderful job themselves.
26. "The Death of Gwen Stacy" by Gerry Conway, Gil Kane, John Romita and John Tartaglione (Amazing Spider-Man #121-122) - 393 points (4 first place votes)
Gerry Conway had only been the regular writer on Amazing Spider-Man for roughly a year when artist John Romita decided that he wanted to shake the series up by killing off a major character. Initially, he considered the standby when it comes to "Who should we kill off in Spider-Man's series?," which is Aunt May. Conway, though, suggested that it might make more sense to take out Gwen Stacy, who Conway wasn't a big fan of (he felt that she and Peter were too much of a "perfect couple" and it wasn't interesting) and Romita agreed that her death would have a greater impact.
In the “Death of Gwen Stacy,” Norman Osborn finally snaps for good and, as the Green Goblin, kidnaps Peter Parker’s girlfriend, Gwen Stacy and then throws her off of a bridge…
Whoa, whoa, whoa, Spider-Man! I know that your girlfriend was just murdered in front of you, but you don't have to use such strong language like "creep"! By the way, Conway himself was the one who asked for them to add the little "snap" there when she dies, which later leads readers to logically assume that her neck snapped when Spider-Man's webbing grabbed her.
Anyhow, Gerry Conway, Gil Kane and John Romita practically DARE you not to come back for the next issue with that ending and they were surely right. The following issue is a powerful lesson in Spider-Man’s humanity and his capacity for mercy, as he just can't bring himself to kill the Green Goblin when the opportunity arises. It's basically a matter of, "If I kill to avenge the woman who loves me, aren't I therefore becoming someone that she never would have loved in the first place?"
Of course, a somewhat underrated aspect of this story is the way that Conway uses this story to set up the romance he wanted between Peter and Mary Jane, as seen in the classic epilogue to the story (which is the first half of a bookend Conway uses during his run).
Conway built Mary Jane up so much in his run that when he finishes it, he uses the other half of the aforementioned bookend and it works really well.