I feel just horrible, here I am level 21 and Lydia has been a faithful companion and mostly good company since the beginning!   I decided to do a quest today where I had to get that shield for a particular Jarl, the dungeon was full of necromancers and adepts and I was having a hard time with 5 at once plus their summonings!    In the confusion I was whirling about wildly with my enchanted mace, smiting the hethen left and right when out of the corner of my eye I noticed Lydia was injured, and down on her knees!   I swirled about to help but I was still finishing my previous swing and alas I clouted poor Lydia across the noggin and down she went 

I felt so horrified that I had killed her that I went on a mad killing streak and destroyed the rest of the necromancers and their boss!   But then I had to consider life without Lydia ... I couldn't, I had to reload and start again 

How has your Lydia met her untimely end?