Valentin Wolfenstein (19 April 1845 – 3 February 1909) was a Swedish-American photographer who worked both in Stockholm and Los Angeles, California. He was one of the first photographers to use flash-lamps for photography.
He owned the first successful photography studio in Los Angeles where he photographed many famous Californians in the 1870s in 1880s.
After returning to Sweden, Wolfenstein owned Atelier Jaeger, the official court photographer's studio in Stockholm, from 1890 to 1905. He was a pioneer in his field and possibly the first in Sweden to make interior pictures in theaters using flash-lamp photography. He took pictures of theater scenes and actors' dressing rooms. A particular skill he developed was taking "look-alike pictures", a double exposure technique that combined images of the same person in two different poses, for example, sitting and standing.