The Bowline Knot
While many climbers and mountaineers swear by it, I admit that I never use this knot. The Bowline knot greatly reduces a ropes breaking strength. It reduces a ropes strength somewhere on the order of 1/2 the force necessary to break the line, or worse. The other major drawback to the Bowline is that it slips when not under a load. It has some perks too, although I don’t personally think it outweighs legitimate concerns over its usage as a tie in knot. It is easy to tie, and easy to untie after it has been loaded.