James Tennant Baldwin (May 6, 1933 – March 2, 2018), often known as Jay Baldwin or J. Baldwin, was an American industrial designer and writer. Baldwin was a student of Buckminster Fuller; Baldwin's work was inspired by Fuller's principles and, in the case of some of Baldwin's published writings, he popularized and interpreted Fuller's ideas and achievements. In his own right, Baldwin was a figure in American designers' efforts to incorporate solar, wind, and other renewable energy sources. In his career, being a fabricator was as important as being a designer. Baldwin was noted as the inventor of the "Pillow Dome", a design that combines Buckminster Fuller's geodesic dome with panels of inflated ETFE plastic panels.

J. Baldwin, born the son of an engineer, once said that, at 18, he heard Buckminster Fuller speak for 14 hours non-stop. This was in 1951 at the University of Michigan, where Baldwin had enrolled to learn automobile design because a friend of his had been killed in a car accident that Baldwin attributed to bad design. He worked with Fuller prior to graduation from U. of M. in 1955. During his student years, Baldwin worked (in a unique job sharing role) in an auto factory assembly line. He went on to do graduate work at the University of California, Berkeley.

Baldwin remained a friend of Buckminster Fuller, and reflected that "By example, he encouraged me to think for myself comprehensively, to be disciplined, to work for the good of everyone, and to have a good time doing it."

As a young designer in the late 1950s and early 1960s, Baldwin designed advanced camping equipment with Bill Moss Associates. In the early 1970s, Baldwin taught at Pacific High School, and later taught simultaneously at San Francisco State College (now called San Francisco State University), San Francisco Art Institute, and the Oakland campus of California College of Arts & Crafts for about six years.

The period 1968-69 found him both a visiting lecturer at Southern Illinois University and the design editor of the innovative Whole Earth Catalog. The Catalog came out in many editions between 1968 and 1998, and Baldwin continued to edit and write for both the Catalog and an offshoot publication, CoEvolution Quarterly, later renamed Whole Earth Review.

Baldwin was at the center of experimentation with geodesic domes, an unconventional building-design approach – explored by Fuller – that maximizes strength and covered area in relation to materials used. He also dove enthusiastically into the application of renewable energy sources in homes and in food-production facilities, working with Integrated Life Support Systems Laboratories (ILS, in New Mexico) and with Dr. John Todd and the other New Alchemists involved with "The Ark" project. Baldwin's initial involvement with solar energy was during that very experimental, ad-lib phase when much was moving from principles or theory into actual development. In the 1970s, at ILS, he was the co-developer of what was touted as the world's first building to be heated and otherwise powered by solar and wind power exclusively.

At Prince Edward Island, Baldwin perfected his greenhouse design: successfully maintaining banana trees. He used several water tanks filled with tilapia, as a source of natural fertilizer for his hydroponics system. His greenhouse included a volume of compost for the production of heat, which was recirculated by ceiling fans. All of these are now the staples for the components of modern greenhouse construction design.

Baldwin referred to his own rural home as "a three-dimensional sketchpad".