Gustav Adam Maass Jr. (1893–1964) was an American architect working primarily in the Mediterranean Revival style who designed public buildings and private homes in and around Palm Beach, Florida, from the 1920s until his death in 1964.

He received a degree in architecture from the University of Pennsylvania in 1917, and worked during World War I in the U.S. Civil Service at League Island Navy Yard in Philadelphia.

After the war, Maass returned to Birmingham, where he designed a variety of structures, including a Masonic Temple, power plants, schools, churches, and houses.

[2] In 1921, Maass joined Harvey and Clarke in West Palm Beach, where he participated in the design of many buildings in Delray Beach in the 1920s; his Art Deco style was reflected in commercial buildings along Atlantic Avenue.

The Palm Beach Town Council has designated several Maass-designed houses as landmarks to be preserved, many of which were in the Mediterranean Revival style featuring simple windows, barrel clay tile roofs, and stucco exteriors.