Thomas Brentnall (30 December 1846 – 10 July 1937) was an English-born chartered accountant who was the first president of the Institute of Chartered Accountants in Australia.
He was the nephew of Thomas Brentnall, the 9th Mayor of Middlesbrough (1862). He matriculated at the University of Durham.
His successful business evolved with several names, Brentnall & Riley, Brentnall, Norton & Co., and Brentnall, Mewton & Butler. From 1880, he lived at Newnham, Caroline Street, in South Yarra.
Brentnall was a keen musician and most notably a violinist and often performed in Melbourne.
His wife, Caroline Brentnall (née Crossley) died in 1909.