Antonina Mascarenhas Monteiro, more popularly known as Tuna Mascarenhas, (June 13, 1944 – September 9, 2009) was a Cape Verdean activist and medical laboratory scientist.
She served as the First Lady of Cape Verde from 1991 until 2001 during the tenure of her husband, President António Mascarenhas Monteiro.
Mascarenhas also founded the Cape Verdean Children's Foundation to provide services, such as daycare centers, to poor children and their families.