Thomas Cowan (5 December 1839 – 14 September 1890) served one term as a member of the South Australian House of Assembly for the Electoral district of Yatala.

Cowan, his parents and four younger siblings emigrated to South Australia, arriving in Adelaide on 3 August 1852.

His father later purchased property at Two Wells (39 km north of Adelaide) where Cowan assisted with the operation of several businesses including a farm, a tavern and a post office.

Cowan served on the District Council of Port Gawler as a councillor from 1868 to 1872 and as the chairman from 1873 to 1875.

The vacancy was subsequently filled by Richard Butler who had unsuccessfully stood for the seat earlier in 1890.