TOD
Just going through the current series of Doctor Who gives a nice list of guest stars:
Zoe Wannamaker as Lady Cassandra O'Brien ("The End of the Earth", "New Earth")
Simon Callow as Charles Dickens ("The Unquiet Dead")
Penelope Wilton as MP (later Prime Minester) Harriet Jones ("Aliens of London", "The Christmas Invasion")
Simon Pegg as The Editor ("The Long Game")
Anne Robinson as Anne Droid ("Bad Wolf")
Daniel Evans as Daniel Llewellyn ("The Christmas Invasion")
Anthony Stewart Head as Headmaster Finch ("School Reunion")
Catherine Tate as Donna Noble ("The Runaway Bride")
Dekek Jacoby as Professor Yana ("Utopia")
John Simm as The Master/Harold Saxon ("The Sound of Drums")
Plus the third Christmas special, "Voyage of the Damned," brings us Kylie Minogue, Geoffrey Palmer, and Bernard Cribbens.
Torchwood, on the other hand, has avoided having very many names as guest stars, limiting themselves to James Marsters as Captain John Hart ("Kiss Kiss Bang Bang") and Alan Dale as Aaron Lopley ("Reset").
A week from Friday, at least on the American SciFi Channel, brings us Samantha Bond as Mrs. Wormwood in the first episode of The Sarah Jane Adventures: "The Invasion of the Bane."
(And this doesn't even bring in how Freema Agyeman, Naoko Mori and Eve Myles all started out in smaller roles, before moving on to co-star status. Or how John Barrowman instantly moved into co-star/star status. And, come to think of it, Catherine Tate is turning into the newest co-star...)
SWW, Dr.Who has had a great cast of guests over the last few years.
Bernard Cribbens was in the movie release of Dr Who that featured Peter Cushing as the Doctor. I will admit - I actually own that movie. Some of the effects were pretty cheesy. They based the movie on an episode of the show from the first or second season of the original series. HE was also in Fawlty Towers with John Cleese.
Here is a link for the Dr. Who movie.
http://imdb.com/title/tt0060278/BTW, John Cleese guested on the original series in a Tom Baker storyline "City of Death" with Eleanor Bron.
There was s Children in Need special segmant this past winter that had David Tennant and the fifth doctor, Peter DAvison. It was cute!