Doctor Who Series 9: Who Are The Hybrids And What Does It All Mean?
4. From The Wirryn To Professor Sorenson
Let's look farther afield now to some of the show's classic adventures and some of the most notable appearances of hybrids; if The Witch's Familiar suggested that the legend of the hybrid was what drove the Doctor from Gallifrey then it is feasible he has encountered other hybrids long before series nine.
In the second Fourth Doctor serial The Ark In Space, the Doctor, Sarah and Harry encountered humanity in cryogenic suspension under attack from an insectoid alien called the Wirryn. While the Doctor was able to save humanity from destruction he did encounter a Human - Wirryn hybrid when crewmember Noah became infected and led an alien attack on his own race.
A year later the Fourth Doctor and Sarah encountered Professor Sorenson, the sole survivor of a expedition to the planet Zeta Minor in Planet Of Evil. Possessed by a creature from a universe of antimatter, Sorenson is transformed into a hybrid creature known as Anti Man. This time the Doctor was able to save Sorenson but there is always a chance some of the hybrid influence remained.
Could we see reference to these classic tales in the new storyline? Anything is possible.