Rudolf Knoll was a German opera singer born on November 4, 1926, in Bergzabern, Germany, and he passed away in 2007. He was a baritone who had a distinguished career in opera, performing from 1951 to 1960 at the theaters in Regensburg, Oldenburg, and Aachen. From 1960 to 1963, he was engaged at the Zurich Opera House. Knoll also made guest appearances at prestigious venues such as the Vienna State Opera, the State Theater Wiesbaden, and the Stuttgart State Opera.

He participated in the world premiere of Heimo Erbse's opera "Julietta" at the Salzburg Festival on August 12, 1959, and sang the title role in the premiere of Rudolf Kelterborn's "Kaiser Jovian" at the State Theater Karlsruhe on March 4, 1967. Knoll also performed at the Turin Opera in 1962 and 1968, and from 1967 to 1969, he sang at the Metropolitan Opera in New York, where he performed roles such as Kothner, Biterolf, and Faninal alongside renowned artists like Walter Berry, Reri Grist, Leonie Rysanek, Christa Ludwig, and Nicolai Gedda. In 1969, he was a guest at the Los Angeles Opera House.

From 1971, Knoll was associated with the Mozarteum in Salzburg, serving as a full professor of solo singing from 1975 to 1995. He also worked in opera direction. His extensive repertoire included roles such as Alberich, Jago, Pizarro, Gunther, Beckmesser, Faninal, Mandryka (performed with Montserrat Caballé), Renato, Rigoletto, Luna, and Dr. Schön.