Henry Nelson O'Neil was born in St Petersburg, and was primarily a painter of historical genre pictures. He was a member of "The Clique" based in St John's Wood.

O'Neil achieved enormous success with "Eastward Ho" in 1857, one of the greatest Pre-Raphaelite pictures. The painting, which exactly caught the public mood, showed troops embarking at Gravesend to reinforce the army at the time of the Indian Mutiny. The picture is highly emotionally-charged, showing the wives, sweethearts, and families, outlined against the great black flank of the ship, about to separate them. The wealth of detail is wonderfully done, and the facial expressions of the distressed women captured with clarity and sympathy. In 1859, the sister painting "Home Again" was also a great and well-deserved success.

In later years O'Neil did not manage to maintain his artistic career at this level, but still produced excellent paintings, for instance "The Last Moments of Raphael" in 1876. He became ARA in 1879. Henry O'Neil also wrote poetry and songs, and was a friend of Millais.