What: One of the earliest mini figure memories I have is getting a big bag of mono color, cheap plastic robots at the dollar store. I was never that attached to them but they were always there, hanging out alongside my much more cherished MUSCLE and Monster in My Pocket figures. Fast forward more than two decades and I finally discover some details about this line, called Ro-Gun Robots (thanks to MinifiguresXD, formerly Toypedia, for shedding some light via an informative post a few years back). This set consisted of six unique sculpts, each of which came in three colors: dull blue, dull red and black. They're made of a hard, light plastic that would probably crack pretty easily if bent (I haven't tried). One part of me kind of likes these and another part doesn't think they're incredibly exciting. In any case, they're a welcome addition to any mini figure army, especially if you have a weakness for robots and/or cheapo toys.
When: The MinifiguresXD entry linked above says 1984, but I'd estimate that I got mine in the late 1980s or very early 1990s so it seems they were being sold for a while.
Where: U.S. (at least). I remember getting mine at a variety/dollar store, but I have also seen people say they found them in toy vending machines.
Who: Made by Arco