Barbara Stanisława Trzetrzelewska (born 30 September 1954), better known by the mononym Basia, is a Polish singer-songwriter and recording artist noted for her Latin-inspired jazz-pop music.

She began singing professionally in various Polish bands from the late 1960s throughout the 1970s, then relocated to the UK in 1981. She rose to fame as a singer in the British trio Matt Bianco. By 1986, Basia and her bandmate Danny White had left the group to focus on her solo career.

She signed on with Epic Records and enjoyed a successful international career between 1987 and 1995, particularly in the USA where her first two albums Time and Tide and London Warsaw New York were platinum-certified, million-unit sellers. During that period, her biggest hits were "Time and Tide", "New Day for You", "Promises", "Baby You're Mine", "Cruising for Bruising", and "Drunk on Love". She had also built up a fan base in Asia.

She took a lengthy hiatus due to personal tragedies, then made a comeback to regular recording and performing in the late 2000s. She currently releases her music through independent labels.

Basia was born in Jaworzno, Poland in 1954. She had three siblings – two brothers and a sister – and her parents ran a popular ice cream parlor in the town's centre. Growing up in a musical household, Basia enjoyed singing from an early age and had an extensive collection of vinyl records. Her mother played piano and gave her first music lessons.

In 1969, Basia debuted as a vocalist in local band Astry and performed with them at the National Festival of Beat Avangarde in Kalisz where they came first. Always good at exact sciences, Basia was intending on studying mathematics at the Jagiellonian University, but eventually took up physics. On the first year of the course she was approached by the manager of the popular Polish all-female band Alibabki who offered her performing with the group. Basia accepted the offer, dropped out of the university and started to perform with Alibabki in 1972. She toured with them in Poland and abroad, mostly in the Eastern Bloc countries, until 1974. In 1976, Basia took part in the National Festival of Polish Song in Opole as a soloist to no success. From 1977 to 1979, she performed in Polish rock band Perfect.

Basia relocated to London with her partner in January 1981 and went on to record demo tracks for various artists. It was there that she met Danny White (brother of jazz guitarist Peter White) and his collaborator Mark Reilly by answering their ad in Melody Maker. The trio performed in 1983 as Bronze, but later changed the name to Matt Bianco. Their debut album Whose Side Are You On? was released in 1984 and turned out a hit across Europe. It spawned Matt Bianco's UK Top 40 singles "Get Out of Your Lazy Bed" and "Half a Minute". ...