Thomas Baltzar (c. 1630 – 24 July 1663) was a German violinist and composer. He was born in Lübeck to a musical family; his father, grandfather, and great-grandfather were all musicians. Sources suggest an array of music teachers who may have taught him in his early years. According to the writings of Samuel Hartlib, composer and violinist Johann Schop was one of those instructors. Baltzar may have studied the violin with Gregor Zuber and composition with Franz Tunder. He may have also received instruction from composer and violinist Nicolaus Bleyer, who taught Baltzar's younger brother.
Through contacts at Germany's embassy in Sweden (where, by 1653, Baltzar was employed), he may have come in contact with English musicians accompanying Bulstrode Whitelocke's mission to Queen Christina. This possible encounter may have been the impetus for Baltzar's decision to emigrate to England in 1655, leaving behind his newly attained position of Ratslutenist of Lübeck (he had returned briefly to his home city, probably shortly after Christina's abdication in June 1654). Hartlib's writings indicate that the Swedish ambassador to England, Christer Bonde, took in Baltzar. Two years later, according to Anthony Wood, he was employed as a private musician for Sir Anthony Cope at Hanwell House in Banbury. He was given an annual salary of £110, a high figure for the time.