I cut an LED off an old addressable strip I had laying around, but I wasn't sure what controller it used.

Based on the fact it was a 1 wire LED I knew it either a WS2812 or a WS2812B. I started testing it with Adafruit's Neopixel library. From there I just guessed RGB configurations until I found a combination that worked as expected:

The data pin is connected to GPIO14 on the ESP8266 directly (I skipped out on a terminating resistor and a capacitor across the Vcc on the strip because I'm only using a single LED with very short wires, if I was using multiple I probably couldn't get away with skipping those)