I've held off on this one...knowing I wouldn't get a mention on anyone else's responses, but curious to see who else has been mentioned. I've seen a few of the usual suspects come up, so I've naturally decided to go with a designer who hasn't been featured so far...
...another Aussie game designer.
(he doesn't seem to have done much on G+ lately, so it's probably a bit silly linking to his profile there, but I feel dirty linking to Facebook.)
The Peril Planet Website can be found HERE
The DrivethruRPG Shopfront can be found HERE
Nathan is the founder of Peril Planet games, while also being a drama teacher, father, and all round nice guy who lives in Newcastle, just north of Sydney, Australia.
I first met Nathan almost a decade ago at GenCon Oz 2008, but had known him a little while before that online through forums such as Storygames and 1km1kt. I've since been to his house at least once, visited his gaming club in Newcastle, and generally stayed in contact via online means. When I met him he had just released a quirky little game called "Space Rat", which has been out of print for a while now.
Most people who do know of him, probably know of the game FU (Freeform / Universal) which he released in about 2010, and has seen over 5000 downloads. This has been one of those fun little games that has developed quite a following with numerous hacks around, along with plenty of translations into languages beyond English.
Nathan doesn't have a whole lot of stuff on DrivethruRPG, but he always seems to be working on some new project when he isn't busy educating a future generation of creative students.
Have a look at his stuff, there's some great ideas within.