Johannsen is a surname of German origin, commonly found in various countries, particularly in Europe and North America. It is derived from the given name Johann, which is the German form of John. The name often signifies "son of Johann" and can be associated with various historical figures and families. In addition to being a surname, Johannsen may refer to notable individuals in different fields, such as science, literature, or the arts. For example, Wilhelm Johannsen was a prominent Danish botanist known for his work in genetics and the concept of the gene.