I see plenty of opportunity in the Doctor Who/Torchwood universe.
In the Torchwood
episode "Reset," Martha Jones is captured while sneaking around a medical facility and has parasitic larvae implanted in her. I see no reason to waste the opportunity to take her mind off her sacrifice.
Then there's "Cold War" in Doctor Who
. An unidentified man and woman show up on a crashed Russian sub in the 1980s. They discover another unwanted guest relatively quickly but what if there had been more time? Perhaps they could have been interrogated, with a sadistic officer who has been stuck under the ice cap too long having his way with her. Perhaps a crewmember loses hope in their rescue and decides to go out with a bang with the only woman he's seen in months.
In "Nightmare in Silver," the Doctor has to battle the Cyber-Planner for control of his own mind and body with Clara not always being completely sure which she is dealing with. I would have loved to see the Cyber Planner attack her just to piss the Doctor off. In fact, I'm sure there's no shortage of enemies that could have used threats to Rose, Martha, Amy, or Clara to get to the Time Lord.
We've also seen episodes where alien races plan on using Earth for a breeding ground. Surely there has to be a species that needs to plant its young inside a humanoid womb.