Lionel Thomas Courtenay (1 December 1879 – 11 July 1935) was an Australian businessman and politician. Born in Sydney, he left school at a young age but became general manager of an engineering company. He was involved in local politics, sitting on Mascot Council, Mosman Council and Sydney City Council. In 1932, he was elected to the New South Wales Legislative Council as a member of the United Australia Party. He left the Council in 1934 to contest the Australian Senate as a UAP candidate for New South Wales, in which he was successful. However, he died on 11 July 1935, 11 days after he formally became a Senator,^[1] necessitating the appointment of Guy Arkins to replace him.^[2]

Courtenay was born on 1 December 1879 in Balmain, New South Wales, the son of Catherine (née Gleeson) and Lionel Lewis Courtenay. His mother was born in Ireland, while his father, an engineer, was born in England. He attended Gardeners Road Public School in Rosebery.^[1]

Courtenay left school at the age of fourteen and began working as a messenger boy for J Tylor & Sons, a sanitary and hydraulic engineering firm. He was later promoted to travelling salesman, eventually becoming general manager of the Australian division and securing an ownership stake.^[3] Outside of Tylors, Courtenay helped establish the NRMA in February 1920, serving as the inaugural treasurer but resigning within the year to protest staff reductions.^[1] He was also a director of radio station 2SM.^[3]

Courtenay married dressmaker Anne Elizabeth Lee in 1902, with whom he had six children. He died at his home in Willoughby on 11 July 1935, aged 55. He was interred at Rookwood Cemetery.^[1]

Prior to his death, after being diagnosed with terminal cancer, Courtenay offered to donate his body to medical research, either for medical experimentation during the remainder of his life or for post-mortem examination. The offer was made to former prime minister Billy Hughes, the federal minister for health, who stated that it was "a tragedy that no sooner had he achieved the summit of his ambition, when the portals of a wide political life were opening to him, than he fell upon the threshold".^[5] John Cumpston, the director-general of health, accepted Courtenay's offer and directed that a post-mortem examination be performed to aid knowledge of metastatic cancer.^[1]