Xena: Warrior Princess and Hercules: The Legendary Journeys use to have the same actors playing different characters all the time. I used to love spotting them and dedicated a gallery to them called The Hall of Recycled Actors.
I don’t know of any other shows that have deliberately done this except Doctor Who and only with one actor. Peter Capaldi played the character Caecilius in the Doctor Who episode The Fires of Pompeii and now he’s the new face of the Doctor.
There are some actors whose face you never see because they are hidden under prosthetics but you recognise their voice. Take Andreas Katsulas for instance. He played G’Kar in Babylon 5 and I had a hate love relationship with that character. He also played Romulan leader Commander Tomalak in Star Trek: The Next Generation. I didn’t recognise the face but I recognised Katsulas’ voice. He was playing a conniving Romulan so hated him straight away.
I love when an actor makes me fall in love with a character in one show then manage to make me passionately hate them in another. I’m dedicating this section to those actors. Welcome to I loved you in this. I hated you in this.