On 05 Nov 1806 William Ponsonby 1st Baron Ponsonby of Imokilly in County Cork (age 62) died. His son John Ponsonby 1st Viscount Ponsonby (age 36) succeeded 2nd Baron Ponsonby of Imokilly in County Cork. Frances Elizabeth Villiers Viscountess Ponsonby (age 20) by marriage Baroness Ponsonby of Imokilly in County Cork.

On 22 Feb 1855 John Ponsonby 1st Viscount Ponsonby (age 85) died at Brighton. Viscount Ponsonby of Imokilly in Cork extinct. His nephew William Ponsonby 3rd Baron Ponsonby of Imokilly in County Cork (age 39) succeeded 3rd Baron Ponsonby of Imokilly in County Cork.

In 1861 William Ponsonby 3rd Baron Ponsonby of Imokilly in County Cork (age 45) died. His first cousin William Ponsonby 4th Baron Ponsonby (age 54) succeeded 4th Baron Ponsonby of Imokilly in County Cork.

In 1866 William Ponsonby 4th Baron Ponsonby (age 59) died. Baron Ponsonby of Imokilly in County Cork extinct.