Sita Maria Dias Valles (Cabinda, 23 August 1951 - Luanda, 1 August 1977) was a member of the PCP (Portuguese Communist Party), in charge of the UEC (União dos Estudantes Comunistas or the Communist Students' League).
She was tortured and brutally murdered following the events of May 1977, presumably in August 1977 in Luanda, Angola.