Her father was an Austrian character actor and stage producer Josef Danegger [de] (real name, Joseph Deutsch: 1865–1933) who later took over as director of the City Theatre in Zürich.

She started her performing with children's roles, making her debut in 1912 at Max Reinhardt's Deutsches Theater in Berlin, with a further youthful appearance there in 1914.

Waniek had connections with the "German Theatre" at Brno (in the former Czechoslovakia), where, until 1933, Mathilde Danegger was making regular guest appearances.

[3] With the German change in government at the start of 1933, Mathilde, a staunch antifascist, fled to Switzerland where she worked at the National Theatre in Zürich with Wolfgang Langhoff, like her a political exile from Nazi Germany.

Between 1948 and 1951 she also wrote, as Cultural Editor, for Unsere Stimme, a regional communist news magazine based at Villingen-Schwenningen near the border with Switzerland.

Of particular note was her portrayal of Frau Holle in the 1963 film of the eponymous fairy tale by Gottfried Kolditz and her television role in "Mutter Jantschowa" (1968).

[4] Her third husband, the university lecturer and author Herbert Crüger, became caught up in the political persecution that was a feature of East Germany in the 1950s.

At a secret trial in December 1958 he was found guilty of "high treason" ("schweren Staatsverrats") and sentenced to an eight-year jail term.