Ronaldus Shamask (born November 24, 1945) is an American fashion designer.
Ronaldus Shamask was born in Amsterdam, Netherlands and raised in Australia. He was trained as an architect and is self-taught in fashion design. He started his professional career a window display designer in Melbourne (1963–1966). He went on to become a fashion illustrator for The Times and The Observer in London, England from 1967 to 1968.
From 1968 to 1971 Shamask was a theatrical designer for the Company of Man performance group in Buffalo, New York. He worked as a freelance interior and clothing designer between 1971 and 1977. In 1978–1990 he formed a partnership with Murray Moss and formed the Moss Shamask Fashion Company in New York. He went on to design many more clothes. Ronaldus has won several awards since then.