Kimmie Meissner won the world championship in her first appearance at worlds. It is rare for a skater to do that. The only ones I know of are:
Oksana Baiul 93
I am not sure if Debi Thomas did that in 1986. Was it her first appearance at worlds?
Are there any other skaters that achieved this rare feat?
BTW in Kimmie's case although this was her first WORLDS appearance, she competed at the Olympics prior to this. So this was not her biggest competition, still a very impressive feat.