Kelly Kapoor and other characters who transformed entirely over the course of a show
Watching the first season of The Office is unnerving for a number of reasons. The show was trying very hard to recreate exactly what the original UK version did, but it just wasn't working. Before it figured out how to be its own, wonderful thing, there's just some noticeably odd things happening at Dunder Mifflin at the start. Michael had truly awful slicked-back hair, there's some employees we see but never meet or find ever again (https://theoffice.fandom.com/wiki/Background_Employees?file=Pilotemployees.jpg) and, most notably, whoever the hell Kelly Kapoor was supposed to be.
Mindy Kaling's character starts off as demure and buttoned-up with nary a hint of what the beloved Kelly she would eventually evolve into: a bubbly, boy-crazy person you could only describe as b-a-n-a-n-a-s. It's SO weird to see Season 1 Kelly because...that's not Kelly! I'm so glad the writers decided to do a complete 180 with her, because that first Kelly prototype was no fun.
Of course, Kelly Kapoor isn't the only character to make huge transformations over the course of their respective show. I think Parks and Rec went through similar growing pains in their first season and eventually learned not to make Leslie Knope something of a female Michael Scott and instead made her the powerhouse we'd come to know and love.
Which characters' major transformation arcs stick out with you?