John William Ponsonby, 4th Earl of Bessborough

John William Ponsonby, 4th Earl of Bessborough also known as Lord Duncannon (31 August 1781 - 16 May 1849) was an English politician. He hailed from the prominent Ponsonby family of Cumberland. He was First Commissioner of Works under Lord Melbourne (1831 - 1834), briefly Home secretary (1834), and Lord Privy Seal (1835 - 1839). Later, he was briefly Lord Lieutenant of Ireland from 1846 under Lord John Russell.

{| border="2" align="center" |width="30%" align="center"|Preceded by:
Frederick Ponsonby |width="40%" align="center"|Earl of Bessborough |width="30%" align="center"|Followed by:
John George Brabazon Ponsonby |}