Blas is mainly a Spanish given name and surname, related to Blaise. It may refer to

• Piz Blas, mountain in Switzerland
• San Blas (disambiguation)

• Ricardo Blas Jr. (born 1986) Judo athlete from Guam
• Blas Antonio Sáenz (fl. 1845), Nicaraguan politician
• Blas Avena, American martial artist
• Blas Cabrera Navarro, American physicist
• Blas Cabrera (1878–1945), Spanish physicist
• Blas Cantó (born 1991), Spanish singer
• Blas Chumacero (1905–1997), Mexican trade union leader
• Blas Cristaldo (born 1964), Paraguayan football (soccer) defender
• Blas de Lezo (1689–1741), Spanish admiral
• Blas de Ledesma (1556—1598), Spanish painter
• Blas Elias (born 1967), American drummer
• Blas Galindo (1910–1993), Mexican composer
• Blas Gallego (born 1941), Spanish artist
• Blas García Ravelo (17th century), Spanish sculptor
• Blas Giunta (born 1963), Argentine football player
• Blas Giraldo Reyes Rodríguez (born 1955), Cuban librarian
• Blas Hernández (1879–1933), Cuban soldier
• Blas Infante (1885–1936), Andalusian politician and writer
• Blas María de la Garza Falcón (1712–1767), Spanish settler of Tamaulipas and South Texas
• Blas Matamoro (born 1942), Argentine writer
• Blas Minor (born 1966), American baseball player
• Blas Monaco (1915–2000), American baseball player
• Blas Ople (1927–2003), Filipino journalist and politician
• Blas Parera (1777–1840), Spanish composer
• Blas Pérez (born 1981), Panamanian footballer
• Blas Piñar (1918–2014), Spanish politician
• Blas Roca Calderio (1908-1987), Cuban revolutionary and politician
• Blas Ruiz (16th century), Spanish explorer
• Blas Valera (1545–1597), Peruvian historian
• Blas Villate (1824–1882), Spanish general
• Ismael Blas Rolón Silvero (1914–2010), Paraguayan bishop
• Juan Blas de Castro (1561–1631), Spanish singer, musician, and composer

• Blas de Lezo-class cruiser, a class of Spanish Navy light cruisers
• Spanish ship Blas de Lezo, more than one Spanish Navy ship

• Basic Linear Algebra Subprograms (BLAS), a mathematical software library
• Blas, a word invented by Jan Baptist van Helmont to describe astral radiation
• List of storms named Blas, used for eight tropical cyclones in the eastern Pacific Ocean and for one Medicane in the Mediterranean Sea

• All pages with titles containing Blas
• "Bás, Fás, Blás", a poem written by Dominic Behan