Thomas Thomassen Heftye (10 April 1860 – 19 September 1921) was a Norwegian military officer, engineer, sports official and politician for the Liberal Party.

He was born in Vestre Aker as the son of banker Thomas Johannessen Heftye (1822–1886) and his wife Marie Jacobine Meyer (1826–1895).

His great-grandfather migrated to Norway from Hätzingen, Switzerland in the late eighteenth century, and founded the family company Thos.

In 1892 he took education as a telegrapher, and started working in the Norwegian Army engineer department instead of in the infantry.

He would provide valuable information in the buildup for the dissolution of the union between Norway and Sweden in 1905, which the Liberal Party supported.

He resigned already on 10 April the same year,[4] because Prime Minister Gunnar Knudsen refused to seek a vote of confidence in Parliament, a form of investiture.

[1] This was a problematic question at that time, as Norway had made important steps towards parliamentarism, but not formalized the process with change of government.

[6] Former Prime Minister Christian Michelsen had asked for a vote of confidence following the 1906 general election, and survived.

Knudsen would later sit as Prime Minister from 1913 to 1920, and he used Heftye as an arbitrator in both the national wages board and in irregular labour conflicts.

Previously, during his time as telegraph director, Heftye had started the institution of non-legal wiretapping—a method which was later used in labour conflicts.