Nicky or Nikki is one of the Lawndale High School cheerleaders, specifically the one with dark brown hair in a beehive style.
In "The F Word", where she gains a voice and name, she remarks how it's great when the teachers come out to support the team - "God, I hope they don't talk to us" - and thinks it's normal for Brittany to literally get lost or confused about who she is.
She got into Great Prairie State University: the only place that would take her.
Nicky/Nikki in Fanfiction
She is a recurring figure as she's one of the few non-Brittany cheerleaders we know the names of. Her personality and role varies, though she's usually presented as popular and (as in the show) buddies with Britt.
In Lawndale Fighting Championship, she was given the surname Dowling.