Hardware/microcontroller people write code to do interesting things. Sometimes the code isn't as interesting as the whole system or application but you get lured in anyway. The miracle of the adafruit magnetometer driver or MQTT client isn't in the elegance of the code (although its not awful) its that it exists at all and it works. Anyway presented in no order:
Ian Lesnet from dangerous prototypes
Michael Ossmann and Dominic Spill from great scott gadgets
Limor Fried from adafruit
There's innumerable folks in the ham radio community who both solder and code like Hans Summers from qrp labs or Wayne Burdick from elecraft. I like the GPS clock discipline system Hans created, its not the pinnacle of esoteric control theory but its very solid engineering in that it works with minimal resources. Good engineering is making the best you can under the limitations, not like IT type work where the more baroque the better seems to reign as a value.
Ben Heck counts too.
A shout out to frankly the entire esp8266 community
the folks behind evilmadscientist (their website is down at this moment)
Nathan Seidle from Sparkfun probably count under "masters of shipping lots of working stuff"
Admittedly this is turning into a list of cool low level hardware projects that involve coding. But they do develop software and I do follow them.