The Wikipedia page for Marvel's Avengers comics uses the following cover for the main illustration:
This comes from Avengers Vol. 3, Issue 38, which according to the Marvel Fandom Database entry has a fairly long list of featured characters (significantly more than appear on the cover).
I'm in the process of updating the caption on that Wikipedia page, which up until earlier today was missing identifiers for several of the depicted characters. The one character I can't definitively identify is whoever's standing near the middle, with their face showing between Captain America and the Scarlet Witch:
Here's the list of featured male characters who I haven't already identified on the cover (in order of my top guesses):
- Living Lightning (Miguel Santos)
- Wonder Man (Simon Williams)
- Black Knight (Dane Whitman)
- Quasar (Wendell Vaughn)
Perhaps someone who has access to the book can clarify who that last character is on the cover?