They might have passed unnoticed by the new Whovians, the one that did not watch the old series. They were among the races rose against the Doctor in The Pandorica Opens, but they whereÂ threatening Earth in the Fourth Doctor adventure, Terror of the Zygons. At leas that’s what BBC is saying here when they are announcingÂ the Zygons’ returnÂ to Doctor Who 50th anniversary special.
The source of the image is, of course, Facebook. Fell free to follow them.