Eleanor Rogers Onderdonk, painter and art curator, was born in San Antonio on October 25, 1884, the second of three children born to Emily (Gould) and Robert Jenkins Onderdonk. Stimulated by the work of her father and her brother Julian Onderdonk, both of whom were talented painters, she began formal art classes in 1913 at the Art Students League in New York City, where she studied under George Bridgeman and John C. Johansen. She later studied landscape painting under John F. Carlson at Woodstock, New York, and developed an expertise in miniature painting under the tutelage of Alice Beckington, Lucia Fairchild Fuller, and Helen Savier DuMond. Her miniature portraits, generally painted in watercolor on paper or ivory, evidence the artist's delicate touch, eye for detail, and skill in capturing the personalities of her models. She exhibited her works in annual exhibitions sponsored by the Pennsylvania Academy of Fine Arts and the Southern State Arts League; she won a prize from the latter organization in 1929.
In 1927 Eleanor Onderdonk became curator of art at the Witte Museum in San Antonio, a position she held until her retirement in 1958. As curator she had little time to devote to her own work, but in her position she promoted art in Texas. She presented exhibitions in a variety of media-photography, ceramics, textiles, prints, painting, and sculpture-from a wide range of periods. In an effort to expose the community to contemporary art she presented exhibitions including such painters as Diego Rivera, Carlos Mérida, and Pablo Picasso, although their work was not popular with the San Antonio public at that time. Onderdonk supplemented the educational value of these exhibitions with lectures by artists and critics such as Thomas Hart Benton, Alexander Archipenko, Walter Pach, and John Ward Lockwood. During her tenure as curator she organized three exhibitions of early Texas artists. Her efforts stimulated interest in Texas art and prompted the San Antonio Museum Association to develop its Texas Collection. She supported contemporary Texas artists by presenting exhibitions of their work and by assisting the San Antonio Art League in organizing the annual Local Artists Exhibition.
The San Antonio Express designated Eleanor Onderdonk "Woman of the Year in Art" in 1955, and the city celebrated Eleanor Onderdonk Day upon her retirement on May 4, 1958. She helped to found the San Antonio Conservation Society and was a member of the San Antonio Art League, the River Art Group, the Texas Watercolor Society, the Texas Fine Arts Association, and the Craft Guild of San Antonio. She died in San Antonio on November 11, 1964. A memorial gallery at the Witte Memorial Museum bears her name. Examples of her work are included in the collection of the San Antonio Museum Association, which honored her contributions as an artist and teacher in the 1975 exhibition The Onderdonks: A Family of Texas Painters. Her work was also exhibited in Texas Seen/Texas Made, a 1986 exhibition organized by the San Antonio Museum of Art.