High Quality Content by WIKIPEDIA articles! Addison Adrianne Forbes Montgomery (formerly Shepherd), is a fictional character on the ABC television series Grey`s Anatomy and Private Practice. She is played by Kate Walsh. Addison is a world-class neonatal surgeon with board certifications in both Obstetrics and Gynaecology and Maternal and Fetal Medicine. Additionally, she is a medical genetics fellow. She works at the Oceanside Wellness Group, a fictional practice located in Santa Monica, California.