X-Men have had some near escapes over the years....and some frankly stupid endings. I mean bloody illogical, moronic, slapdash resolutions that make no sense whatsoever.
Not that that's always a bad thing. Sometimes it can be pretty cool. I've only listed a few, I'm sure you can think of others so mention them if they come to mind and say whether you thought it was a good move or not.
Onslaught - This started out as an interesting idea. I remember Mark Waid's issue of Uncanny with Jean being hounded by the repressed negativity of Xavier being very good. It was topped ten years later by Morrison's 'sshhh', issue when Emma Frost and Jean entered Xavier's mind and were confronted with some wacked out symbolism. Anyway the idea of Xavier's darker half asserting itself was cool. Then it turned out to be Magneto. 'cough'. Then it was turned into a company wide crossover that removed the heroes of Marvel into a pocket dimension. That was pretty deus ex-ey - an interesting storyline shunted into a relaunch of several titles. Less Ultimatized more null and void.
Scarlet Witch - Pick. I didn't mind Disassembled so much reading it in the trade, but I assumed Scarlet Witch's trials were over for now. Her role in the House of M took it a bit too far. 'No more mutants', was meant to clear house and it did, but seems like the baby got thrown out with the bathwater. Peter David is one of the few writers to try and deal with the consequences of M-Day (don't talk to me about New Warriors...a bunch of ex-mutants acting nothing like they did before...written by the guy who made those wonderful Underworld films...grrr).
Xavier 'dying' - it was a clone. It was a shapeshifter. He was regrown in a vat by Moira. Bishop restored the timeline. Cassandra Nova shot her own body in the head after switching minds knowing full well it would regenerate. Man just die already. Oh and the movie apparently has him possess the mind of a previously unmentioned twin upon death (always handy to have a spare lying around).
The Legacy virus - this was a controversial one. The Legacy virus storyline was started with good intentions, I believe. Still the writers couldn't match it up to AIDS/HIV - though it was generally recognized to be an allegory for that real world tragedy. Instead Legacy was defined as an airborne viroid that would strike randomly - meaning less popular characters were toast. Two Rasputins died due to it....they're both back now. Ah well.
Madrox dying - in honour of Madrox week, Jamie did die. Then it was revealed it was a dupe. Which was convenient.