In L. Frank Baum's first book, The Wonderful Wizard of Oz (1900), we are introduced to a race of people called Hammer-Heads... and sometimes they are called "Wild Ones."
It seems that they have no arms, flat heads and elastic necks. They attack people by swinging their heads at people, then retracting them afterwards. Here we see the Hammer-Heads in attack mode, with a cheering audience!
They seem happy about attacking the Scarecrow. He don't seem so happy.
Here is a more contemporary view as drawn by Greg Hildebrandt.
This seems more in line with my own vision of how they might appear. They even make an appearance in the Broadway musical play, Wicked.
They're still quite happy, so it seems. In my books, Magician of Oz and Shadow Demon of Oz, I wrote about them, though young Jamie Diggs and his best friend, Buddy visit them only in passing. In my newest book, which is nearly complete, they make yet another appearance in name as trading partners with the Hoppers & Horners. Perhaps some day I may visit their mountaintop in another adventure in Oz.
James C. Wallace II
Royal Liaison to Princess Ozma