Peterolsen Groth Hjalmar Seierstedt Falk (2 April 1859 – 2 November 1928) was a Norwegian linguist and philologist.

A professor of philology at the University in Kristiania for about thirty years, he is particularly known for his etymological dictionary of the Norwegian and Danish language in cooperation with Alf Torp.

[1] After this he taught in Oslo while continuing research, especially on Germanic languages and Nordic mythology, including scholarship stays in Germany and England.

Falk received the Crown Prince Gold Medal in 1885[2] and was appointed a docent.

He is particularly remembered for his etymological dictionary of the Norwegian and Danish language, which he wrote in cooperation with Alf Torp.