What does Gael mean?
A name of disputed origin, now very popular in Spanish-speaking countries (notably through actor Gael García Bernal). It is usually tied to Brittany, either as a short form of the Breton Gwenael (gwenn 'white, blessed' + hael 'generous') or to the Gaels, the Celtic peoples. No single etymology is firmly established.
What does Thiago mean?
A form of Tiago, drawn from Santiago ('Sant Iago', Saint James) by resegmenting San-Tiago. The 'Th' spelling is Portuguese-influenced and hugely popular across Latin America. Ultimately traces to the Hebrew Ya'aqov (Jacob), via James.