These are custom-molded connectors that are specifically designed for mating with SNES controllers. Great if you want to add an arcade controller to your project without splicing any wires. SNES controllers use a super-simple clock/data/latch system to send 16 bits of button data, that works with pretty much any microtroller. So they're great for a game or robotic project that needs a bunch of buttons. A nice write up here shows the pinout and protocol

Matches standard classic SNES controllers and SNES-controller-compatibles (a few different styles of SNES controllers are out theres)

SNES connector (10:16)