I created the Vanilla JS site.
I didn't coin the term "Vanilla JS" - it's like asking someone if they invented the term "Blue Chair". Blueness and Chairness have been things for thousands of years, and similarly, "Vanilla" in the software world usually means "plain" - Plain JS. I remember seeing it used before I created the site.
The Google Trends data for the term "Vanilla JS", which indicates that the term came into widespread use in August 2012, coincides with the registration date of the vanilla-js.com domain name. So, while I didn't invent the term, I probably popularized it. This is funny, since I really don't like the term "vanilla" meaning "plain" - but, it's what the software community uses, so in the interest of clarity (and comedy), it's what I chose to use.