Buffy’s Jenny Calendar in the 24 Cherished TV/Movie Teachershttp://www.whedon.info/Buffy-s-Jenny-Calendar-in-the-24.html
Also, we've got some special trivia on Janna of the Kalderash Gypsies:
During her time on Buffy, Robia LaMorte became a born-again Christian.
The character was originally intended to be named "Nikki Calendar", but this was changed to avoid on-set confusion with actor Nicholas "Nicky" Brendon.
For the two episodes she appears in during the first season ("I Robot, You Jane" and "Prophecy Girl") and in the second season premiere ("When She Was Bad"), Jenny's first name is never uttered -- other characters only refer to her as "Ms. Calendar". It's not until the second episode of the second season, "Some Assembly Required", does she get a first name. This happens when Jenny asks Giles to refer to her as such by saying, "Please, call me 'Jenny'. Ms. Calendar is my father."
The death of Jenny was never originally meant to occur. The original plan had been for Oz to be the character who met their end at the hands of Angelus, but that plan was changed after the fan reaction to Oz had been so positive. The grisly demise was then dealt to the character of Jenny.