First spotted in Harry Potter and The Philosopher’s Stone as wand-maker Mr Ollivander, Hurt famously took on the role of The Doctor and The War Doctor in The Name of the Doctor, The Night of the Doctor and The Day of The Doctor.
Roger Lloyd Pack
Even the dearly departed Trigger himself popped up in both shows. Roger Lloyd-Pack played Barty Crouch Senior in Harry Potter and The Goblet of Fire and created the Cybermen as John Lumic back in 2006.
She zoomed on her broom as Madame Hooch in Harry Potter but we saw considerably less of Zoe Wanamaker when she made her Doctor Who debut in 2005. She provided the voice for Lady Cassandra, a large piece of skin stretched on a frame.