Thomas Hoyne (February 11, 1817 – July 27, 1883) was elected Mayor of Chicago in 1876, but his election was later declared null and void by a Circuit Court. Prior to 1876, Hoyne had led a political career in which he had occupied numerous state and municipal offices.

Hoyne moved to Chicago in 1837, where he turned his back on the mercantile life he had been leading and studied law, being admitted to the bar in 1839. He was elected Chicago city clerk in 1840.^[7] In 1853, he was appointed United States District Attorney for Illinois. Six years later, he became a US Marshal for the northern district of Illinois.

In 1863, Hoyne traveled to New York and then to Boston to acquire a lens for a telescope for the University of Chicago. In Boston, he met with Alvan Clark and purchased an 18½-inch lens and mounting for the Dearborn Observatory, at the time, the largest refracting telescope ever built. By 1866, he became one of the founding members of the Chicago Astronomical Society and served as the organization's secretary.^[8]

Following the Great Chicago Fire of 1871, Hoyne presided at the meeting that established a free library in Chicago and sat on its board of directors, eventually writing the first history of the Chicago library system.^[9] He served as president of the board.^[10]

On September 17, 1840 he wed Leonora Temple.^[15]

Hoyne's younger brother Philip Augustus Hoyne served as Clerk of the Recorder's Court of Chicago and (from 1853 until 1858) United States Commissioner for the District of Illinois.^[2] He also served on the Chicago Board of Education, serving two consecutive terms as its president.^[2]