Elizabeth I

Elizabeth I was the Queen of England during the 16th century, and an apparent spouse of the Tenth Doctor.

Biography
The Doctor first encountered Elizabeth I as an image on the Time-Space Visualiser. He, Barbara, Vicki and Ian witnessed her attempting to influence William Shakespeare's to write another play featuring the character of Falstaff —�this one featuring Falstaff "in love". (DW: The Chase)
 * The implication is that Elizabeth was commissioning The Merry Wives of Windsor, a nod to an historical legend in which Elizabeth actually was the impetus for the writing of Merry Wives. However, The Chase does not explicitly name the work, nor give a definite date for this encounter.

Elizabeth I's court astrologer John Dee was apparently another identity of Jared Khan, who was still fruitlessly hunting the Doctor at the time. At this point, the Queen appeared to be on friendly terms with the Doctor, then in his seventh incarnation. (NA: Birthright)

Elizabeth's relations with the Doctor's tenth self were more complicated. He met her after she had met him. This meant there was a back story of which he was unaware. From his perspective, they first met in 1599. On that occasion, in the Globe Theatre, she considered him an enemy of the Crown and ordered her guards to kill him. (DW: The Shakespeare Code)

Sometime after his adventure on Bowie Base One, he returned to 16th century England, where he met Elizabeth for the first time — from her perspective. He told Ood Sigma that he married "Queen Bess", and implied that "her nickname" no longer applied. Elizabeth had multiple nicknames including "the Virgin Queen" and "Good Queen Bess" (BFA: The Marian Conspiracy), but as the Doctor stopped mid-sentence, what precisely he was referring to remained unclear. Later, when the Doctor met Elizabeth X, she made a passing remark stating that "the Virgin Queen" was indeed the nickname the Doctor had been referring to. (DW: The Beast Below)

Alternative timelines
An alternative version of the Doctor met another version of Elizabeth I: Gloriana of an England with its own star fleet. (DWU: A Storm of Angels)

Behind the scenes
Following the broadcast of The Shakespeare Code, it was persistently rumoured that an adventure featuring Queen Elizabeth I and the Tenth Doctor would be forthcoming. However, one never came in series 4, and pre-broadcast information about the 2009 specials did not seem to favour the return of Elizabeth, either. The fact that Elizabeth was mentioned in The End of Time therefore came as a surprise to many fans who had long since resolved that this would remain a mystery with the departure of the Tenth Doctor.