The Fourth Sign is a public artwork by the American artist Tony Smith situated on the lawn outside the Art Building at the University of Hawaiʻi at Mānoa, in Honolulu, Hawaii.

The large sculpture is fabricated in steel, painted black, and signifies the fourth Zodiac sign, which is Cancer (a crab).

In this way the sculpture defines its own "interior" and "exterior", and while open to the sky offers a startling sense of safe haven and enclosure.

In 1978, the Honolulu-based artist and professor of religion, John Charlot, described how quickly the university community made Smith’s sculpture its own:When he returns to Hawaii, Smith will see students draping their young bodies over his sculpture and nestle within the circle of its arms, just as they bathe under the pool under Manoa falls.

He contemplated two other projects for the campus (Haole Crater and Hubris), but only The Fourth Sign was realized.