Luís Manuel Gonçalves Marquez Mendes, GCIH is a Portuguese lawyer and politician, and a former Leader of the Social Democratic Party.

The Social Democratic Party is a liberal-conservative political party in Portugal that is currently the country's ruling party. Commonly known by its colloquial initials PSD, on ballot papers its initials appear as its official form PPD/PSD, with the first three letters coming from the party's original name, the Democratic People's Party. A party of the centre-right, the PSD is one of the two major parties in Portuguese politics, its rival being the Socialist Party (PS) on the centre-left.