Doctor Who: EVERY NuWho Villain And Monster Ranked Worst To Best

It had to be them.

The Master should be added as a dictionary definition under the word "frenemy". Indeed, a lot has transpired since the Doctor and his childhood best friend used to run across the pastures of red grass on Mount Perdition. As Missy nonchalantly put it to Clara: "He keeps trying to kill me. It's sort of our texting. We've been at it for ages."

She also remarked that theirs is "a friendship older than your civilisation, and infinitely more complex". It's also the most compelling dynamic within the show, one where we've been fortunate enough to have seen two absorbing Doctor-Master combinations in David Tennant and John Simm, and with Peter Capaldi and Michelle Gomez.

Simm's Master mirrored Tennant's Doctor with the sharp suits (we'll forgive his hoodie, human eating phase) and displayed charismatic cunning. Gomez is wonderfully electrifying as Missy, with her beguiling belligerence and hypnotic gaze that can quicken the pulse one moment then deaden it (quite literally) the next. Each incarnation perfectly embodied their respective show running eras - the high-energy of Russell T Davies, and the mesmerisingly mind-bending of Steven Moffat.

Sacha Dhawan brings a mixture of Jack Nicholson's flamboyant and Heath Ledger's fierce Jokers to his incarnation; he even shares the same purple colour scheme as the Clown Prince of Crime. And he can bust a move like Joaquin Phoenix's Joker.

Lest we forget Derek Jacobi's brief but memorable turn in Series 3's Utopia, who chillingly conveyed the change from Professor Yana to the Master with just the look of his eyes - as Davies described it: "How do actors do that? I just think that's stunning."

From parading as a prime minister to resilient redemption, the Master/Missy is, alongside the Doctor, the most intriguing and watchable character in the show.