Karl Erb (13 July 1877 – 13 July 1958) was a German tenor vocalist who made his career first in opera and then in oratorio and lieder recital. He excelled in all these genres, and before 1920 gave classic performances of key roles in modern works, and created lead roles in those of Hans Pfitzner. He was the first husband of Maria Ivogün and was considered by many the ideal Evangelist in the St Matthew Passion of Johann Sebastian Bach.
Erb was born in Ravensburg. As a child, he was enrolled in the local Liebfrauenkirche charity choir and music class. His mother taught him to love poetry and he excelled at school. His voice did not break abruptly, but deepened and intensified to a beautiful and spiritual timbre. He was sought out for private musical events and performed in amateur theatre at the Ravensburg Konzerthaus. He later worked at Wolfegg and at Rot as cashier for the State Gas and Waterworks. In 1902, the Konigliche Hoftheater in Stuttgart burnt down, and the company worked temporarily in Ravensburg. Erb, assisting the choir in Cavalleria rusticana, was noticed by Joachim Gans zu Putlitz . Von Putlitz had been appointed Theatre Intendant at Munich long before through the personal efforts of Richard and Cosima Wagner, cf Ernest Newman, and offered a chance to sing solo. He declined, but further offers were made.
In 1906, aged 29, he started an unpaid probationary year at Stuttgart (beginning January 1907, which led to a five-year paid contract. He had the help of a young répétiteur, a singing teacher, a drama tutor (Hans Islaub, who got rid of his Swabian accent) and a ballet master. He studied the roles of Max (Der Freischütz), Lionel (Martha), Walter (Die Meistersinger von Nürnberg) and Mathias in Der Evangelimann by Wilhelm Kienzl. Through the singer Elsa Wiborg, he was given the chance to sing privately for the King and Queen; then, on 14 June 1907, he made his debut in Evangelimann at the new Hoftheater. Erb was also gave recitals and made oratorio appearances during his probation at Stuttgart.