Robert Llewellyn Sumwalt (July 8, 1895 – January 24, 1977) was an American engineer and academic. Sumwalt was born in Baltimore on July 8, 1895. He began undergraduate studies at Delaware College in 1914, belonged to the Sigma Nu fraternity there, and received a B.S. degree in 1918, for which his thesis was "The Design of A Type Emergency Mill Building".