Dancerella was a doll (about 12-16" maybe?) that was dressed up as a ballerina in a leotard with hot-pink tulle tutu. She was produced by Mattel in the 1970s and was a highly popular Christmas gift in the year of 1978, so i'm told.
Dancerella was battery-operated and had pointed down feet to help her dance and on her head was a crown with a knob that you pushed up and down. As you pushed it, she would kick one leg up and spin on the other!
I sure loved Dancerella, mine is gone now due to a nasty parental divorce, but I still keep an eye out at garage sales and on eBay to see the ones they have. They just don't make dolls like her anymore!