Gustaf Nils Arvid Nyblæus (11 December 1907 – 21 February 1988) was a Swedish Army officer, equestrian competitor, coach, judge and official.

[2] Nyblæus' father was a major general in the Swedish cavalry and the chairman of the Jury of Appeal for the equestrian events at the 1912 Summer Olympics.

At the 1948 Summer Olympics he headed the Swedish equestrian team and served as secretary to Carl Bonde, who oversaw the dressage competition.

He again acted as Swedish chef d'equipe at the 1956 Olympics, and at the 1960 Games started a two-decades-long career of dressage judge.

In 1965 he was elected as a board member of the International Federation for Equestrian Sports and later promoted to Chairman of the Dressage Committee.