There are a lot more witches in the books than in the show! Following are the ones I’ve used in my stories to date.
I’ve had a lot of fun casting this character for various stories. The casting depends on the characterization. My first Amelia for the Back and Forth world and the Comfortably Numb world is Rachel McAdams.
For the UN-iverse as well as the Gift Horse Series, I picture Emily Blunt.
For Given Unsought and the INNER-Verse, I picked Ellen Page.
For Not Without Action, I changed to Amy Acker.
I had fun with this character in Not Without Action; I visualized Justin Bartha.
Hallow (Marnie Stonebrook)
I don’t think the “Marnie” in the show really “counts” as Hallow–since the “witch” part of her was so different. Anyway, I’ve “cast” two actresses in the role. For the UN-iverse, I pictured Milla Jovovich.
For other times I’ve used this character, including in the Back & Forth world and The Trunk Trilogy, I’ve drawn my inspiration from Gabrielle Anwar.
My first “casting” was for the Back & Forth universe. I pictured CCH Pounder.
For the Comfortably Numb universe, I changed to Loretta Devine.