Bowstring Knot

The Bowstring Knot is an ancient knot that is used as an eye for bowstrings. The knot is simple and strong. Once tied and pulled firmly, you do not want to untie it: you might call it a good 'tie-once' loop knot. The bowstring knot is appreciated because it is small, strong, secure, and easy to tie. It's neat because it does not have loose ends. Modern archers prefer fixed spliced loops. If the loose (cross marked) end is not secured within the loop between the bow and loop, it is wise to add a small overhand knot as stopper.

Originally from http://www.realknots.com/knots/sloops.htm