Agnes, Viscountess Wenman (died 1617) was an English Roman Catholic woman, under suspicion of involvement at the time of the Gunpowder Plot of 1605.
She was the eldest surviving daughter of Sir George Fermor of Easton Neston in Northamptonshire, by his wife Mary, daughter and heiress of Thomas Curzon.
John Morris with the lady at whose house John Gerard, the Jesuit missionary, while disguised as a layman, had a keen discussion with George Abbot, the future archbishop; it was on the eternal state of a puritan who threw himself from a church steeple because he was assured of salvation.
Sir Richard testified that he "disliked their intercourse, because Mrs. Vaux tried to pervert his wife."
She is noted as the translator of the works of Johannes Zonaras from the French of Jean de Maulmont.