Not exactly a movie, actually an animated miniseries (actually, several).
The "Marvel Anime" series, they all feature an heroic, unknown japanese character that borders on the Mary Sue, which befriends or earns the respect of the main Marvel protagonist (or becomes a love interest), and then dies tragically near the end (performing a heroic sacrifice, usually), which is a terrible blow to the hero, who then proceeds to deliver some sort of eulogy about how there's great people in Japan also, and other rubbish about honor and We're Not So Different After All and blech.
I don't oppose it on principle, but it's not very subtle. At least in the X-Men one they used an existing Marvel character called Armor (which still seems to be the POV character for the viewers) and doesn't die at the end, but still proves to be completely crucial to the solution of the plot for being a special snowflake somehow.
There's also always a tragic japanese villain, of course, but that's at least to be expected and not terrible IMO. I also hate the super ninja assassin with Wolverine-like regeneration powers that shows in half of the series as "honourable antivillain who then teams up temporarily and everyone thinks is supercool even tho he remorselessly killed innocent people close to the hero".