Lady Agnes Fo(r)ster (died 1484) was a wealthy English woman.
He had been Lord Mayor of London and he died a rich man and Agnes and his son William were his executors.
Her gift was commemorated by a brass wall plaque,[1] which read: Devout souls that pass this way, For Stephen Foster, late mayor, heartily pray; And Agnes, his spouse, to God consecrate, That of pity this house made, for Londoners in Ludgate; So that for lodging and water prisoners here nought pay, As their keepers shall answer at dreadful doomsday!
[1] Agnes appears as a central character in William Rowley's (1586–1626) play A New Wonder, a Woman Never Vexed, based on her life.
In the book it said that Agnes met a man at the prison and paid off his debts and married him.