Det. Caitlyn "Cat" Sullivan
Leo Romba
Capt. John Baker
Eddie Esposito
Dr. Monica Pena
Gregg James
Frankie Sullivan

Ally Walker

Frankie Sullivan

Ally Walker plays Frankie Sullivan on the new NBC series "Taxi Brooklyn."
Walker has made her mark in both television and film, beginning her small-screen career on the daytime soap "Santa Barbara," followed by parts in "Moon Over Miami" and "Profiler."

For three seasons, Walker played an ATF agent on FX's critically acclaimed motorcycle club series "Sons of Anarchy," and she also recently appeared in Lifetime's "The Protector." She also received strong notices in the HBO series "Tell Me You Love Me. "

Other series in which Walker has appeared include "Matlock," "L.A. Law," "Wings," "The Shield," "Law & Order," "Boston Legal," "Southland" and "Law & Order: SVU."

On the big screen, Walker first appeared in Cameron Crowe's cult classic "Singles." This was followed by the action film "Universal Soldier" as well as "Steal Big Steal Little" and "While You Were Sleeping."

Walker made her New York stage debut in Alan Ball's "Five Women Wearing the Same Dress," alongside Thomas Gibson and Allison Janney. Recently, she returned to New York to appear in the final all-star cast of Nora and Delia Ephron's "Love, Loss and What I Wore."

Walker has always been an environmental and child welfare activist, supporting such organizations as Environmental Defense Fund and Children Youth and Family Collaborative. She is most proud of her documentary, "For Norman... Wherever You Are." It chronicles her experience through the Los Angeles foster care system, a journey that she was inspired to take after helping a mother and her one-year-old boy get off the streets. This film raised awareness of the flawed but necessary system and was essential to enacting significant reform not only in Los Angeles, but throughout California. Additionally, this heartfelt project won best documentary feature at the San Fernando Valley International Film Festival, as well as the Champion of Conscience Award at Wine Country Film Festival.

Born in Tennessee and raised in Santa Fe, New Mexico, Walker studied biology and chemistry at the University of California, Santa Cruz and went on to work for a genetic engineering firm in San Francisco. While spending a semester at Richmond College of the Arts in London, Walker became interested in theater but did not pursue it as a career in lieu of her education in the sciences. After graduating with a science degree, she continued to work in genetic engineering until she was spotted in an L.A. restaurant and cast in her first project.

She currently resides in Santa Monica with her husband, sons and three dogs.