Sir Thomas Frederick Halsey, 1st Baronet, PC, DL (9 December 1839 – 12 February 1927) was an English Conservative Party politician who sat in the House of Commons from 1874 to 1906.

Halsey came from one of the most prominent families of Hertfordshire, whose seat was at Gaddesden Place, near Hemel Hempstead.

His father was Member of Parliament (MP) for Hertfordshire from 1847 until he was drowned with his wife and his younger son in the shipwreck of the steamer Ercolano in the Gulf of Genoa on 24 April 1854.

[4] After his parliamentary defeat, he once again devoted himself to county affairs, serving as chairman of the St Albans Quarter Sessions from 1908 to 1918.

He finally retired from the Hertfordshire Yeomanry with the rank of lieutenant-colonel, having served as second-in-command, and then joined the county Territorial Force association, becoming its chairman.