"The Horror at Martin's Beach" is a short story by American writers H. P. Lovecraft and Sonia H. Greene.

It was written in June 1922 and first published (as "The Invisible Monster") in November 1923 in Weird Tales (Vol.

The creature bears strange anatomical irregularities such as a single large eye and rudimentary forelegs and six-toed feet in place of pectoral fins.

Some months later, the vessel with the creature breaks free from its moorings in a storm and disappears.

The rescuers and the captain are seemingly hypnotized and pulled into the water by the creature's apparently vengeful mother, to the horror of an onlooking crowd.