20 Doctor Who Characters Who MUST Return
9. The Mara
The Mara is a far more sinister Doctor Who villain than the slightly embarassing pink snake would have you believe. This is a creature that feeds on people's darkest impulses, latching onto them and turning them into agents of chaos.
The Mara was referenced in The Legend of Ruby Sunday, so RTD or another writer can easily reintroduce the so-called "God of Beasts" to modern Doctor Who. It would be a perfect opportunity to bring back Janet Fielding, and give us the final battle between Tegan and the Mara.
Unleashing the Mara on contemporary Earth may tread too close to Empire of Death, but a smaller-scale, character-driven story would be an absolute treat – think The Devil's Chord crossed with Amy's Choice. Minus the singing, dancing, and dodgy ponytails.