Sir Pierce Thomas Lacy, 1st Baronet, JP, KCSG (16 February 1872 – 25 December 1956) was an English stockbroker.

Lacy was born in Edgbaston, Birmingham, the second of five sons (there were four daughters also) of Wexford-born John Pierce Lacy (1839-1906) of Oakmount, Edgbaston, and his second wife, Mary, née Conick (died 1914).

John Pierce Lacy was chairman of Docker Brothers Ltd and a former partner in a galvanisers and iron merchants business, who bought controlling interests in the Kynoch ammunition makers and Brown, Marshalls and Co. Ltd., manufacturers of railway carriages, and made a success of both.

He was created a Baronet in the 1921 Birthday Honours for his contributions to finance[3] and appointed High Sheriff of Suffolk for 1927/28.

In 1898, Lacy married Ethel Maud, daughter of James Finucane Draper, of St Helier, Jersey.