I have never heard of a Saint Jill. But the name Jill originally came about as a diminuitive, or nickname for the name Julia. Saint Julia was a 5th century martyr who died at Corsica.
Jill Dickerson's birth name is Jill Courtney Dickerson.
Jill Maragos's birth name is Jill Kasperczyk.
Jill Streater's birth name is Jill Streater.
Jill Taggart's birth name is Vuerhard, Jill.
Jill Andre's birth name is Jill A. Kline.
Jill Biden's birth name is Jill Tracy Jacobs.
Jill Cordes's birth name is Jill Lynette Cordes.
Jill Lieber's birth name is Jill Ann Lieber.
Jill Sharp's birth name is Jill Ann Zawacki.
Jill Tweedie's birth name is Jill Sheila Tweedie.
Jill Ritchie's birth name is Jill Susanne Ritchie.
Jill Ireland's birth name is Jill Dorothy Ireland.