The fisherman's knot is a bend (a knot for joining two lines) with a symmetrical structure. The fisherman's knot is also known as angler's knot, English knot, halibut knot, waterman's knot, and true lover's knot.

The bend consists of two overhand knots, each tied around the standing part of the other. It is compact, jams when tightened, and the working ends can be cropped very close to the knot. It can easily be tied with cold, wet hands.

These properties are well-suited to fishing, so the fisherman's knot is often used with fishing line. However it can slip when using modern nylon monofilament line, which is more slippery than historic fishing materials. If more holding strength is required, the overhand knots can be made with more turns, as in the double fisherman's knot, and triple fisherman's knot. Other knots sometimes provide superior performance with nylon lines, such as the blood knot.

In knitting, this knot is used to join two strands of yarn. In this context, it is commonly known as "the magic knot".