Baron Greenwich was a title in the Peerage of the United Kingdom that has been created twice in British history.

This was to follow Charles II bestowing the titles of Duchess of Cleveland, Countess of Castlemaine, Baroness Limerick, and Baroness Nonsuch upon his other mistress, Barbara Palmer; the title of Viscountess Shannon upon his first mistress, Elizabeth Killigrew; and the titles of Duchess of Portsmouth, Duchess of Aubigny, Countess of Fareham, and Baroness Petersfield to yet another mistress, Louise de Kérouaille.

However, Charles died on 6 February 1685, having never followed through on his original plans to ennoble Gwyn.

[2] The first official creation came in the Peerage of Great Britain in 1767, when Lady Caroline Townshend was made Baroness Greenwich, in the County of Kent, with remainder to the male issue by her second husband, Charles Townshend.

The second creation came in the Peerage of the United Kingdom in 1947 when Lieutenant Philip Mountbatten, on the morning of his wedding to Princess Elizabeth (who became Queen Elizabeth II), was made Baron Greenwich, of Greenwich in the County of London.