Roger Palmer, 1st Earl of Castlemaine, PC (3 September 1634 – 21 July 1705) was an English courtier, diplomat, and briefly a member of parliament, sitting in the House of Commons of England for part of 1660.

This made it more of a humiliation than an honour: [...] and then to the Privy Seal, and sealed there the first time this month; and, among other things that passed, there was a patent for Roger Palmer (Madam Palmer's husband) to be Earl of Castlemaine and Baron of Limbricke in Ireland; but the honour is tied up to the males got of the body of this wife, the Lady Barbara: the reason whereof every body knows.Palmer did not want a peerage on these terms, but it was forced on him; and he never took his seat in the Irish House of Lords (although he did use the title).

[5] Palmer showed unwavering and public devotion to Roman Catholicism, in spite of heavy legal and social penalties, and also staunchly supported the Stuart monarchy.

He had to represent himself and, as shown by the verbatim account in the State Trials, secured his own acquittal with skilful advocacy in his own defence against Judge Jeffreys and Chief Justice Scroggs.

[7][8] After the Revolution of 1688, Castlemaine fled for refuge to Llanfyllin near his ancestral home in Montgomeryshire and stayed for a while in the house of a recusant there,[9] but he was arrested in Oswestry, Shropshire, and committed to the Tower,[10] spending most of 1689 and part of 1690 there.

Castlemaine's heirs included his nephew, Charles Palmer of Dorney Court, to whom he left property in Wales which had come to him from his mother's family, but it proved to be heavily encumbered and worth little.