Rita Repulsa is the first main villain of Power Rangers, appearing in the very first episode of Mighty Morphin Power Rangers. Long ago Zordon sealed her in a space dumpster on the moon and AFTER TEN THOUSAND YEARS SHE WAS FINALLY FREE, TIME TO CONQUER EARTH! With the help of her lackeys, she creates monsters of the day to destroy the Power Rangers though after they defeat her monster she gets A MASSIVE HEADACHE. She would eventually marry Lord Zedd and the two continued to harass the Rangers until they were both hit with an energy wave that turned her good.
Rita later appeared in Power Rangers Mystic Force as Mystic Mother, in a twist of irony she was the source of this Rangers teams connection to the Morphin Grid.
In the reboot movie, Rita remained pretty much the same except that she and Zordon were on the same ranger team before she turned evil.
In an alternate timeline, she successfully turns Tommy evil which leads to him turning into Drakkon who in turn kills her.
Barbara is as classic as a classic could classic, many times imitated but no one could really could come close to her. What else can I say, a fun campy and distinct villain performance.
Of the two that did follow in Barbara's weird outfit, I thought they did fine more or less. While Carrie does show a bit of range and does come closer to Goodson she just isn't as good, son. It sounds more put on and even goes a little reptilian at times.
Susan is a different Rita and I think they were going for that she has a smoother voice but when she yells you can hear the OG Rita come out...but just doesn't fit right. She doesn't get a lot to work with so maybe if she had time she could have got into the role more but as is, she is just fine and is Rita enough for what they need.