The Winkies are residents of the Winkie Country in the Land of Oz. They prefer the color yellow in their clothing and landscaping.
The Winkies were enslaved for many years by the Wicked Witch of the West who made them work hard and treated them cruelly. When she ordered some to kill Dorothy and her friends they were not of a brave people and were scared off by the lion's roar. When Dorothy melted the witch, there was great rejoicing, and the day was set aside as an annual holiday. The people asked the Tin Woodman to be their emperor, and he gladly accepted and has ruled them successfully ever since. (The Wonderful Wizard of Oz)
In the MGMfilm the Winkies had green skin. They did not speak until after the Witch was melted, and then seemed to be coming out of a trance. They also chanted a Yoo-Heeve-Hoo song.
In The Wiz, the Winkies were funny looking people who had very small eyes and mis-shaped faces, They were forced to work in a sweatshop with no lunch breaks, until Dorothy destroyed Evillene. Once Evillene was gone, the shedded there original forms and became normal looking people.