Karl Julius Heinrich Yens (also known as Karl Jens), fresco, portrait, and still life painter, as well as engraver and illustrator, was born in Altona, Germany on 11 January 1868. Yens studied with Max Koch in Berlin and later with Benjamin Constant and Jean-Paul Laurens at the Académie Julian in Paris. He was active as a muralist in Germany and Edinburgh, Scotland before immigrating to the United States in 1901. During the first decade in his adopted country, Yens fulfilled mural commissions in New York City and Washington, D.C.

After settling in Southern California in 1910, Yens was active in Los Angeles and Pasadena before moving to Laguna Beach in 1918. He established his studio which still stands there on South Coast Highway near Ruby Street. Yens exhibited and won a medal in the 1915 Panama California Exposition in San Diego, California. He continued to show widely in Southern California and was a member of and exhibited with the Laguna Beach Art Association; the Association of American Painters and Sculptors; the Los Angeles Art Association; the California Art Club; the California Watercolor Club; the Long Beach Art Association; the San Diego Fine Art Society; the International Bookplate Association, the Academy of Western Painters, and the California Society of Miniature Painters. Yens co-founded the Laguna Beach Art Association and the Modern Art Society and was also a member of the American Federation of the Arts.

In the late 1910s and early 1920s, Yens experimented with the technique of cliché-verre, a method that utilized a glass plate, photo sensitized paper, and the sun to create a photographic image on the paper which he then hand colored. The technique had been developed in France in the 19th century and was used by a number of the Barbizon painters/printmakers.

Yens received numerous awards for his work which is represented in the collections of the Laguna Art Museum, Laguna Beach, California, the Crocker Art Museum, Sacramento, California; and the Smithsonian National Portrait Gallery, Washington, D.C.

Karl Yens died in Laguna Beach, California on 13 April 1945.