Barlow 2 blade pocket knife from the dime store. Starting in 5th grade I had one in my pocket until I was deep into my 20's. Simple, cheap knife, and back then they had good German Solingen steel blades.
Microtech Mini Socom, Blade Date of 9/98 Bought brand new and it's a keeper. Just with I kept some others I had including the Full size double action one.
Got one for free a few years ago, and I carry it everywhere on my keys. It has been very useful for such a small blade, but then again scalpels are small blades too and think of what they can do.
My grandfather's WWII knife, US Army, Pacific theater. Captain, Major on his way home I think. He died in 1984, emphysema, in part because he got malaria in the Pacific. Fought in New Guinea, Mindanao, and at least one other island I can't remember. My older brother talked with him about his war experiences, and the quote I remember most is, "I landed on lots of beaches, and I never saw a Marine."