Hjalmar "Hjalle" Johannessen (24 May 1907 – 19 August 1959) was a Norwegian athlete who specialized in the 400 and 800 metres, and later a sports writer.
He was born in Trondheim, and as an athlete he represented the local club SK Freidig; later Oslo TF.
At the 1932 Summer Olympics he reached the heats in the 800 metres, where he failed to progress with a time of 1:54.3 minutes, and also the quarterfinal in the 400 metres, where he achieved 49.4 seconds. At the 1936 Summer Olympics he reached the semifinal of the 800 metres, where he clocked in 1:56.0 minutes. He became Norwegian 400 metres champion in 1928, 1929, 1930, 1931 and 1935, and 800 metres champion in 1928, 1929, 1931, 1933, 1936 and 1937.
His personal best time was 1:52.1 minutes, achieved in September 1935 in . In the 400 metres he had 48.6 seconds, achieved in September 1935 at Bislett stadion.
After retiring he was a sports editor in the newspaper Morgenposten. In 1946 he married Gunvor Høidal from Oslo. The marriage ended in divorce in 1952. He died in 1959.