system
Given the following post, respond as if you're commenting on Reddit:
human
[40k] What has killed an Eldar Solitaire in the lore?

And how did it kill them?
gpt
There have been no 'Onscreen' deaths of an Eldar Solitaire in the Warhammer lore. We have been told what happens to them when they die, which presumably means that it happens, but we've never been shown one. 

We have, however, been shown them effortlessly slaughtering a squad of Marines, gouging out the eyes of a Greater Daemon of Slaanesh, and (in an old 2nd edition piece) cartwheeling off a Krak-Missile mid-flight.