Gandalf

Gandalf was a character in The Lord of the Rings. In John Waters' drag adaptation of the book, Gandalf the Witch was played by Joan Crawford. (PROSE: Mad Dogs and Englishmen)

When 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)

Later, the Eleventh Doctor said he was "the outer space Gandalf". (HOMEVID: Meanwhile in the TARDIS)

When Ryan Sinclair first saw Basalt's cave laboratory on Adamantine, he commented that it looked like the study of a wizard like Gandalf. Much like the Master and the Eleventh Doctor himself previously, Ryan likened the Thirteenth Doctor to Gandalf, describing her as "sort of Gandalfy." (PROSE: Molten Heart)

Behind the scenes

 * In the real world, Gandalf is a character from both The Lord of the Rings and The Hobbit, by J. R. R. Tolkien.
 * Ian McKellen played Gandalf in Peter Jackson's The Lord of the Rings trilogy; he later provided his voice for the Great Intelligence in The Snowmen. He also made a cameo as himself in costume as Gandalf on the set of The Hobbit in The Five(ish) Doctors Reboot.
 * Fourth Doctor actor Tom Baker was briefly considered for the part of Gandalf in The Lord of the Rings film trilogy; coincidentally, Seventh Doctor Sylvester McCoy would later be cast as Gandalf's fellow wizard Radagast the Brown.
 * Gandalf appears as one of the main characters in LEGO Dimensions.