A great thread, as good a year later as the day it started
figure 8 was most used when I used to rock climb
Figure 8. Darn near does it all.
The Blood Knot (below) is one I learned a few years ago - it's unique in that it maintains most of the inherent strength of the line. We used this to attach a monofilament line to a nitinol antenna on a small spacecraft - didn't want the knot to compromise the strength of the retention line.
Trucker's hitch is one of the ones I remember - having needed to pull my crap-can car for repairs on more than one occasion. Half hitches, with proper relief loops, are probably my go-to knot more than almost anything (though whatever keeps her from getting loose will work just fine.)
Bowline... it's the go-to knot when you want to tie off around something and remove later. Used it a lot rapelling.
I'm shocked how many people tie their shoes the wrong way.
figure 8 was most used when I used to rock climb
This.
Palomar knot and cinch knot twice through for fishing.
Hangman's knot.
Also, lashing.