They might have had their chance to bring back classic monsters from Doctor Who‘s past, but former showrunners, Russell T. Davies and Steven Moffat nonetheless have a couple of suggestions about which aliens should return in the future.
The pair were on BBC Radio 2’s Graham Norton Show on Saturday and were quizzed about which creatures they’d like to see back for Chris Chibnall’s era. It’s no great shock that Moffat, being a big fan of The Ark in Space (because everyone should be), opted for the Wirrn. He went on:

“They’re giant insects, but the old show wasn’t able to do them brilliantly. [It was] a fantastic story, but the special effects weren’t fantastic at that point. I think they’d make a fantastic monster now.”

And quite right too! The idea behind the Wirrn was, essentially, Alien before Alien – they implanted their eggs in other species and when they hatched, they’d overtake the host bodies and convert them into the insect-like beings.
Davies, meanwhile, went for a surprising alien (although another created by Robert Holmes): the Krotons! They’re from… well, The Krotons. He said:

“They were crystallised monsters and if you think about what you could do with CGI now with something made out of crystals – !”

The Krotons isn’t such a well-regarded serial, but I’m happy to admit I’m a fan. Oh, gimme a Second Doctor adventure any day. Yes, the titular monsters have their faults – namely, their skirts and their Brummie accents (no offense to anyone in Birmingham) – but they’re a neat idea and a pretty cool design too.
Russell is, of course, right: because they can reform their own bodies to adapt to new situations, something awesome could be done with them for modern Who.
Which monsters would you like to see back to face Jodie Whittaker’s Thirteenth Doctor? Or would you like to see a clean slate for Series 11?