Try the Datura plant. It is the foulest plant I have grown. It would be informative to know what form of life you would like to deter though.

Rue graveolens is pungent and causes rashes too.

what is it you want to deter? there are a few pretty smelly natives such as Hedgewort.

Mind Boggles in what you want to deter LOL.

There are lots recommended but I haven't grown them because I have cats (and they don't dig!) Rather than copy a list from Google try enquiring there - I just looked and there is quite a list.
If its visitors you don't want try a fresh manure heap by the front gate, lol... (Sorry, must be in a funny mood this evening...)
(Loostrife's reply could be fun as Datura is quite poisonous and interestingly psychoactive...)

Yes, I was at the GC some time ago and came across these seed packets which said in large letters “Give It A Try!” This plant is what is grown in the lower levels of hell. As a matter of fact it’s flowers are known as “Hell’s Bells”.