Nikki McKenna is Bart Simpson's love interest from The Simpsons episode, Stealing First Base.
When Mrs. Krabappel takes a leave of absence, Bart's class has to share a room with the school's other fourth-grade class. Bart ends up having to sit in the back of the class with Nikki, and he gently flirts with her. At first glance, Nikki seems to be bothered by Bart until he asks to draw on her shoulder. Bart asks Grandpa for advice, and his recommendation was to plant a kiss on Nikki. The next day, Nikki and Bart go freestyle on their skateboards, and they end up on top of a slide, where Bart steals a kiss. However, Nikki freaks out and yells in disgust. Nikki's parents later have a meeting with Homer and Marge, and Principal Skinner decides to make a policy of no-physical-contact in Springfield Elementary, or "Hands-Off". After a disastrous school meeting, Nikki surprises Bart in his locker and they smooch. The couple later see First Lady Michelle Obama in U.S. school roof. Bart reveals his feelings for Nikki, but she rejects his feelings again. As a result, Bart stumbles off the roof, causing her to worry until he starts breathing. She performed CPR emergency mouth-to-mouth to save Bart, despite the Hands-Off policy. In the last moments of their relationship, Bart asks why she kept changing her mind about him, to which she states there are things Bart has yet to learn about women, and that is why she'll never tell him. She then says he'll see her later and kisses his cheek; as she walks away, he says he loves her.
She is later seen with her father at Springfield General Hospital, trying to get a vaccine for the "Housecat Virus", only to make way for Mr. Burns when he addressed the crowd.She is seen with her parents as background characters in the school (after he sees his parents in school auction).She reappears in a cameo in Moonshine River, where Bart's visit her house to ask for another chance, but once again, she continues to flip-flop between loving and hating him. Finally, Bart gets frustrated and simply leaves.