Osgyth (or Osyth) (died 700 AD) was an English saint. She is primarily commemorated in the village of Saint Osyth, Essex, near Colchester. Alternative spellings of her name include Sythe, Othith and Ositha.
Born in Quarrendon, Buckinghamshire (at that time part of Mercia), she was the daughter of Frithwald, a sub-king of Mercia in Surrey, and was the niece of St Edith of Aylesbury and Saint Edburga of Bicester. Her mother was Wilburga, the daughter of the pagan King Penda of Mercia.
Raised in a convent in Warwickshire under the direction of Saint Modwen her ambition was to become an abbess, but she was too important as a dynastic pawn to be set aside.
Forced by her father into a dynastic marriage with Sighere, King of Essex, she did her dynastic duty and produced him a son. While her husband ran off to hunt down a beautiful white stag, Osgyth persuaded two local bishops to accept her vows as a nun. Then, eventually, perhaps after Sighere's death, she established a convent at Chich, in Essex, where she ruled as first abbess.