Haliotis gigantea, common name the giant abalone, is a species of sea snail, a marine gastropod mollusk in the family Haliotidae, the abalone. It is also known as Siebold's abalone, after Philipp Franz von Siebold.

Description The size of the shell varies between 80 mm and 200 mm. "The very large shell has a rounded-oval, quite convex shape. The distance of the apex measures from the margin between one-ninth and one-tenth the length of the shell. The surface of the shell shows coarse, low, unequal spiral cords and broad wave-like undulations. The typical form of this shell is one of the largest in the genus. It has a rounded-oval outline. The back of the shell is quite convex and highest in the middle. It is solid but not very thick,.