Guilherme Posser da Costa

Guilherme Posser da Costa (born 18 May 1953) is a São Toméan politician. He was the Prime Minister of São Tomé and Príncipe from 1999 to 2001.
Posser da Costa was Minister of Foreign Affairs: 1987-1988, 1990-1991, and 1994-1996. He unsuccessfully ran for President of São Tomé and Príncipe in 2021, losing to Carlos Vila Nova.