Sir Robert Southwell FRS (31 December 1635 – 11 September 1702) was an Anglo-Irish politician and diplomat.

The family had settled in Ireland a couple of generations earlier, and his father had become a customs official at Kinsale in 1631.

However, he remained in favour, being appointed in spring 1680 as an envoy to the Elector of Brandenburg, with the object of constructing an alliance against France.

He died at his estate King's Weston House near Bristol, on 11 September 1702 and was buried nearby in Henbury church in Gloucestershire.

Though he remained living in England Southwell remembered his Irish roots by founding almshouses in Kinsale.

Southwell married, on 26 January 1664, Elizabeth, eldest daughter of Sir Edward Dering of Surrenden-Dering in Kent.

Their children were: Rupert, born on 21 May 1670, and died on 8 May 1678; Edward Southwell, his heir; and four daughters—Helena, Elizabeth, Mary, and Catherine.