I thought it might be interesting to look at who created the various villains / races that have recurred. Of course, the person who wrote their introductory episode didn't necessarily create them but I suppose they did much to flesh them out if they weren't the originator of the actual idea, and also presumably made them popular through the script they wrote.
The Daleks & Davros - Terry Nation
The Meddling Monk - Dennis Spooner
Cybermen - Kit Peddler & Gerry Davies (my understanding is Kit Peddler was the ideas man and Gerry Davies the dramatist in their writing partnership)
The Macra - Ian Stuart Black
The Ice Warriors - Brian Hayles
The Great Intelligence & the Yeti - Merv Haisman & Henry Lincoln
The Autons - Robert Holmes
The Silurians - Malcolm Hulke (one of Doctor Who's most underrated writers in my opinion)
The Master - Robert Holmes (wrote his first appearance in 'Terror of the Autons' but he was really made to order as an ongoing villain and so presumably Terrance Dicks (script editor) and Barry Letts (producer) are really co-creators)
The Sontarans - Robert Holmes
The Zygons - Robert Banks-Stewart
The Mara - Christopher Bailey
Sil - Philip Martin
The Rani - Pip & Jane Baker
The Slitheen - Russell T. Davies
The Judoon - Russell T. Davies
The Ood - James Strong (writer of their first episode but I believe R.T.D is the credited creator)
The Weeping Angels - Steven Moffat
The Silence - Steven Moffat
Those are off the top of the head. I know I'm almost certainly missing a lot so feel free to add them.
KEY
In bold are the ones who have appeared in more than one era (ie the greatest longevity). I've defined this as must be a different Doctor, producer & script editor (classic series) / Doctor and 'showrunner' (modern series) to their initial appearance.
In italics are the ones who have been written by writers other than their creator (ie have had a shelf life beyond the ongoing influence of their creator)
Underlined are the ones who have appeared in both the 'Classic' and 'Nu' series.
The Daleks & Davros - Terry Nation
The Meddling Monk - Dennis Spooner
Cybermen - Kit Peddler & Gerry Davies (my understanding is Kit Peddler was the ideas man and Gerry Davies the dramatist in their writing partnership)
The Macra - Ian Stuart Black
The Ice Warriors - Brian Hayles
The Great Intelligence & the Yeti - Merv Haisman & Henry Lincoln
The Autons - Robert Holmes
The Silurians - Malcolm Hulke (one of Doctor Who's most underrated writers in my opinion)
The Master - Robert Holmes (wrote his first appearance in 'Terror of the Autons' but he was really made to order as an ongoing villain and so presumably Terrance Dicks (script editor) and Barry Letts (producer) are really co-creators)
The Sontarans - Robert Holmes
The Zygons - Robert Banks-Stewart
The Mara - Christopher Bailey
Sil - Philip Martin
The Rani - Pip & Jane Baker
The Slitheen - Russell T. Davies
The Judoon - Russell T. Davies
The Ood - James Strong (writer of their first episode but I believe R.T.D is the credited creator)
The Weeping Angels - Steven Moffat
The Silence - Steven Moffat
Those are off the top of the head. I know I'm almost certainly missing a lot so feel free to add them.
KEY
In bold are the ones who have appeared in more than one era (ie the greatest longevity). I've defined this as must be a different Doctor, producer & script editor (classic series) / Doctor and 'showrunner' (modern series) to their initial appearance.
In italics are the ones who have been written by writers other than their creator (ie have had a shelf life beyond the ongoing influence of their creator)
Underlined are the ones who have appeared in both the 'Classic' and 'Nu' series.





