Axel Theodor Johannessen (29 May 1849 – 2 March 1926) was a Norwegian physician, pediatrician, professor at University of Oslo and senior doctor at Rikshospitalet Hospital in Oslo.
During 1885–1886, Johannessen studied the occurrence of struma and two years later undertook a trip to hospitals in Germany, the Netherlands, Belgium, France and Denmark to study the treatment of tuberculosis.
[2] In 1891 Johannessen was appointed lecturer in childhood diseases at the University of Kristiania.
From 1893 he was also a senior doctor at Rikshospitalet's newly established children's department, and in 1895 he was appointed as a professor in childhood diseases.
Axel Johannessen was awarded the Crown Prince's Gold Metal (Kronprinsens gullmedalje) by the University of Oslo in 1882.