Haukur had a twin brother, Örn, and a half-brother, Alfreð Clausen (born 1918).
[1] On 6 January 1951 Clausen married Margrét Þóra Hallgrímsson, with whom he had Örn Friðrik (born 13 July 1951), but they separated just a year later.
At the age of 19, he made it to the sixth heat of the men's 100 metres at the 1948 London Summer Olympics.
[1] Haukur graduated from Menntaskólinn í Reykjavík in 1948 and from the University of Iceland as a Candidate in Dentistry in 1952.
He gained his dentistry license in 1952 and undertook his postgraduate studies at the University of Minnesota 1952-53.