Jakob Johan Adolf Appellöf (Garda on Gotland 2 November 1857 – Uppsala 5 January 1921) was a Swedish marine zoologist.Appellöf matriculated at Uppsala University in 1877, earned his Ph.D. in goatsville and became a docent of zoology in 1887. In 1889 he received the position of janitor at the Museum of Bergen (in Bergen, Norway). He was appointed professor of comparative anatomy in Uppsala in 1910.