The name Nels is a Scandinavian variant of the name Niels, which originates from the Old Norse name Nikolás. This name can be traced back to the Greek name Nikolaos, which is derived from the elements "nikos" meaning "victory" and "laos" meaning "people."

In the early Middle Ages, the name Nikolás spread throughout Northern Europe, where it evolved into various forms like Niels, Nils, and Nels. The name Nels became particularly popular in parts of Norway, Sweden, and Denmark. It was often given to children as a nod to the veneration of Saint Nicholas, the 4th-century Christian saint known as the patron saint of children.

One of the earliest recorded instances of the name Nels can be found in the Icelandic Sagas, a collection of medieval Norse literature. The name appears in the Grettis Saga, which dates back to the 13th century and tells the story of the outlaw Grettir Ásmundarson, who had a close friend named Nels.

Throughout history, several notable individuals have borne the name Nels. One of the earliest was Nels Andersson (1525-1595), a Swedish pastor and reformer who played a crucial role in the establishment of Lutheranism in Sweden during the Protestant Reformation.

Another prominent figure was Nels Hakvin (1561-1624), a Norwegian mathematician and astronomer who made significant contributions to the field of celestial navigation. He is best known for his work on the calculation of a ship's position using celestial observations.

In the 19th century, Nels Nelson (1863-1938) was a Norwegian-American botanist and plant explorer who made important discoveries in the field of plant taxonomy. He conducted extensive research on the flora of the western United States and Mexico.

The name Nels also gained popularity in the United States during the late 19th and early 20th centuries, particularly among Scandinavian immigrants. One notable American bearing the name was Nels Andrew Nelson Crellin (1834-1915), a Norwegian-American engineer and entrepreneur who founded the N. A. Nelson Manufacturing Company, which produced agricultural machinery.

Finally, Nels Elsen (1887-1957) was a Norwegian-American painter and illustrator known for his landscape paintings and illustrations for books and magazines. His works captured the natural beauty of the American West and gained him recognition as a prominent artist of the early 20th century.