Filming on the special, written by Steven Moffat, starts this week.
Commenting on his casting Grant said: “I played Doctor Who in the digital animated Scream Of The Shalka and I’m honoured to be in the Christmas Special.”
Scream Of The Shalka was an online animated adventure produced to mark the show’s 40th Anniversary in 2003.
Ward, who has starred in BBC One’s in Silent Witness as Harry Cunningham since 2002 also joins the Doctor, played by Matt Smith, and his new companion played by Jenna-Louise Coleman.
Doctor Who returns to BBC One for a seventh series “soon” with a further eight episodes due to air next year
