Siegmund Walter "Sigi" Nissel (3 January 1922, Munich – 21 May 2008, London) was an Austrian-born British violinist who played second violin in the Amadeus Quartet and served as its administrator.
Sigi Nissel was born in Munich to a Jewish family from Vienna.
He began playing the violin at the age of 6.
His mother died when he was 9.
He was taken by his father to Vienna, where his teachers included Max Weissgärber.
Nissel was evacuated from Vienna in 1938 to Great Britain.
During World War II, Nissel was interned as a "friendly enemy alien" in Onchan Camp on the Isle of Man where he met the violist Peter Schidlof and later the violinist Norbert Brainin.
With the British cellist, Martin Lovett, they would form the Amadeus Quartet.
The Amadeus Quartet, informally known as the Wolf Gang, gave its first concert in London in 1948.