Myrtle Elizabeth Johnson (1881 – 1967) was an American marine biologist, ascidiologist, and educator in California in the early 20th century. She was the first woman PhD faculty member at the San Diego State College (now San Diego State University) and was chair of the Biology department for two decades. Her major work, Seashore Animals of the Pacific Coast, published in 1927, was the standard descriptive text of intertidal species until Ed Ricketts's Between Pacific Tides was published in 1939. Ricketts considered Johnson's book "the vade mecum of marine biologists of the Pacific. Indispensible."