Thorstein Aschehoug Lambrechts (6 October 1856 – 11 May 1933) was a Norwegian bookseller.
He was a son of veterinarian Bernhard Gabrielsen Lambrechts (1828-1907) and Karin Bolette Aschehoug (1831–1907).
[2] He took over the parent company H. Aschehoug & Co in 1888 together with William Martin Nygaard.
Lambrechts subsequently operated the bookstore until 1928 when it was purchased by Johan Grundt Tanum (1891-1978).
He became vice chairman of the Norwegian Booksellers Association in 1891, and chaired the organization from 1903 to 1919.