William Molyneux, 2nd Earl of Sefton

William Philip Molyneux, 2nd Earl of Sefton (18 September 1772 – 20 November 1838), also known as Lord Dashalong, was a sportsman, gambler and a friend of the Prince Regent.

He succeeded to the title in 1795 and it passed in turn on his death in 1838 to his eldest son Charles William Molyneux, 3rd Earl of Sefton.

On 20 June 1831, he was created Baron Sefton of Croxteth in the Peerage of the United Kingdom which allowed him to sit in the House of Lords.

In 1836, he founded the Waterloo Cup for coursing at Great Altcar in Lancashire, an event which was very popular in its heyday and attracted large crowds.

His wife, Lady Molyneux, was a Patroness of Almack's club, of which his mother had been a Foundress; she is a minor character in several novels of Georgette Heyer.