I lost a Sunwayman C20C during a wedding, dropped out of my EDC bag and i didnt notice since it was already late in the evening and the lighting wasn't that good. Lucky SOB who found it. Anyway, next day bought a new one online and that's that. Been doubly (even triple) careful since then.
Surefire Titan Plus. Only had it for a week. Put it on an S Biner so I could unclip it from my key ring. Apparently I unclipped it and set it down somewhere while on a trip to Pennsylvania. I really liked that light. Bummer!
Purchased a gunga-modded L-Mini II with a neutral (5C?) emitter years ago. Last saw it March of 2016. Scoured the house, the car...etc...it did everything right, the tint, the form factor, the build quality, the ease of use, and the perfectly flat discharge curve. :-(
I have a stock L-Mini II sitting in a drawer which might need to be modded.
I am always looking to purchase or trade for an L-Mini II to replace that one I lost...
I've lost a bunch, 4 or 5 in the last few years. Fortunately the were all Photon Freedoms. I know one jumped out of my pocket when I pulled out my knife. The washer or the dryer ate at least two. One was a "loan" that never returned. Thankfully, these are inexpensive. No Surefires, HDS, Quarks or Zebras have gone AWOL, those would be painful both for the memories and the $$.
Not many, but some were hard to replace. I'm hoping that my friends accidentally wandered off with them and will find/use them eventually but no sign of it yet. Terrier burying is more likely, unfortunately.
First was an SF A2 Aviator - arguably the most useful flashlight I ever owned, and I am truly embarrassed to have lost it. Still have the case, just not the flashlight.
Next was a Fenix 2AA warm white - the first warm white LED flashlight I saw, and really nice to use outdoors. Don't remember the model and had no luck researching it.
Finally and most recently, somewhere in my house (and probably in my office) is an early Malkoff M60 flood. I took it out of my Z2 to experiment with some incandescent bulbs, and when I went to put it back it was gone. I'm pretty sure that one will turn up.
EDIT - OK, this is embarrassing... I was downloading photos from an old ISP in preparation for closing the account and ran across a picture of some flashlights. In addition to the Aviator I mentioned, there are two other lights that seem to have disappeared as well.
The one on the right is a Fenix L1D and I guess I replaced it with the LD15 I have today, but I don't remember the make/model of the one in the middle. I do remember it being one of the early compact right-angle LED lights designed for use on a MOLLE web, and I remember it being relatively dim and bluish, but I also remember it being surprisingly useful.