Thomas Payne Westendorf (February 23, 1848 – April 19, 1923) was an American songwriter, composer, and educator. Westendorf wrote around 500 musical pieces and songs, but was most famous for his hit song, "I'll Take You Home Again, Kathleen." It was the only Westendorf song that lived long enough to receive rights protection renewal. It was republished many times throughout the years and sung by singers including Elvis Presley, Mitch Miller, Bing Crosby, and Johnny Cash. "I'll Take You Home Again, Kathleen" was listed among the most popular American ballads in 1887, and gained recognition as one of the most beloved songs in music history. It was included in a number of musical collections and used in motion pictures, including Mrs. Parkington and Magic Town. It even made a brief appearance on an early episode of "Star Trek" (September 29, 1966).

Despite the fact that Westendorf became recognized in musical circles and received income from composing, he choose to continue his career in education.

As an educator, Westendorf occupied positions of a teacher, musical tutor, and superintendent in a number of reformatory schools across the U.S. His longest position was as superintendent at Chehalis Reform School. He was one of the first educators to start teaching music in reformatory schools. Westendorf led successful boy choruses, male quartets, and glee clubs in many institutions. His work at reform schools received mixed feedback and often drew controversy. On one hand, many children who studied under Westendorf's supervision were paroled and led successful lives. By some accounts, he managed public funds responsibly and the institutions under his management were praised as model schools. On the other hand, in many cases Westendorf was forced to resign his positions, and often moved from state to state. The reasons for his resignations were unclear, controversial, or accompanied by unspecified "charges."