There are many varieties of stopper knots you can make; which knot you choose depends on your needs, time, and skill level. Make a figure 8 knot to stop a sailing rope from sliding into the mast. First, form a loop by crossing the end of the line or "tail" over the middle part of the line.
How to tie a Stopper Knot animated, illustrated and explained | NetKnots rope knots.

Step-by-step video-guides on how to tie stopper knots, and other useful knots.

Learn how to tie Stopper Knots with step-by-step animation and videos. Master knots like the Overhand Knot, Figure 8 Knot, Estar Stopper, Double Overhand Knot, Stevedore Stopper, Ashley Stopper Knot, and many more.

Also known as the Oystermans stopper, the Ashley stopper knot is of an excellent bulky nature that allows it to serve the purpose of a stopper knot, that is, to prevent the end of a rope from unraveling, passing back through a hole, device or block and slipping through another knot.
To tie an Ashley Stopper Knot, start by making a long, wide bight close to the end of the rope. Next, fold the bight to form two loops, with the smaller of the two loops being closer to the working end and the larger next to the standing end.