Heather Seymour "Judy" Guinness (14 August 1910 – 24 October 1952) was a British fencer.
She won a silver medal in the women's individual foil event at the 1932 Summer Olympics.
The judges had awarded her the gold medal but, in a noted gesture of fair play, she informed them they had failed to count two hits achieved by her Austrian opponent Ellen Preis.She was a daughter of Henry Guinness (d.1945), an Irish engineer, banker and politician.
In 1934 she married the racing driver Clifton Penn-Hughes.
He died in a pane crash and she remarried John Henning in 1942.