Donald Sidney Appleyard (July 26, 1928 – September 23, 1982) was an English-American urban designer and theorist, teaching at the University of California, Berkeley. Born in England, Appleyard studied first architecture, and later urban planning at the Massachusetts Institute of Technology. After graduation, he taught at MIT for six years, and later at the University of California, Berkeley. He worked on neighbourhood design in Berkeley and Athens and citywide planning in San Francisco and Ciudad Guayana. Appleyard gave lectures at over forty universities and acted in a professional capacity in architecture and planning firms in the United Kingdom, Italy and the United States. He died in Athens as a consequence of a traffic collision.