Gandalf

From Tardis Wiki, the free Doctor Who reference

Gandalf was a name used to refer to the Doctor. When the Saxon Master sent a message to Martha Jones via a television broadcast, he showed her the aged Tenth Doctor and sarcastically said, "Say hello, Gandalf." (TV: Last of the Time Lords)

The Eleventh Doctor compared himself to the character, saying he was "the outer space Gandalf". (TV: Meanwhile in the TARDIS)

Behind the scenes

Gandalf