The Butterfly Knot
The butterfly knot is a static loop that can be formed anywhere along a rope, not just on the ends. There are several methods for tying this knot; this is the "around-the-hand method".
Knot Video: How to Tie the Butterfly Knot
Knot Tying Instructions
Step 1 - Hang the rope from your hand, thusly.
Step 2 - Coil it around your hand twice, so that there are three coils facing you.
Step 3 - Reach under the right-most coil and grab the middle one, then carefully pull it out and form a loop. Do not upset that right-most coil.
Step 4 - Bring the loop you made all they way over the coils, and pull it back underneath both remaining coils. Pull the loop, and then both ends of the rope to tighten.