Thorvald Nicolai Thiele (24 December 1838 – 26 September 1910) was a Danish astronomer and director of the Copenhagen Observatory.

[2] In the early 1900s he also developed and proposed a generalisation of approval voting to multiple winner elections called sequential proportional approval voting,[3] which was briefly used for party lists in Sweden when proportional representation was introduced in 1909.

Thiele also was a founder and Mathematical Director of the Hafnia Insurance Company and led the founding of the Danish Society of Actuaries.

It was through his insurance work that he came into contact with fellow mathematician Jørgen Pedersen Gram.

The main-belt asteroids 843 Nicolaia (discovered by his son Holger) and 1586 Thiele are named in his honour.