Thomas Horton M.D. is a fictional character on the NBC soap opera Days of Our Lives. The role was portrayed by John Lupton from July 10, 1967, to May 3, 1971, December 23, 1971, to July 3, 1972, May 9 to 11, 1973, October 24, 1975, to April 27, 1978, and finally from December 22, 1978, to March 7, 1980.