Missy Robinson is the main Antagonist Carly's now-estranged, former best friend. Missy adores Carly but loathes Sam and plots several ways to get Sam out of Carly's life to remain Carly's only best friend. Based on her behavior, she shares similar actions to Valerie, Freddie's girlfriend in iWill Date Freddie. Missy never made another appearance in the series after winning "a six month cruise".
Missy met Carly when their families were stationed at the same naval base at Seal Beach. They eventually grew apart when Missy left Seattle.
When Missy returned to Seattle in the episode iReunite With Missy, she caused a rift to develop within Carly and Sam's friendship. Sam notices that Missy intentionally gives her a fake address that leads her to a factory that makes piñatas (with no candy inside of them, to her dismay) instead of to the skydiving port, then again in the episode drops her phone in Wahoo Punch. To "make up" for these events, Missy gave Sam Persian chocolates to make up for her supposed accidents, however the candy expired in 1992 (and are described to be older than the "Fresh Prince of Bel Air"), giving Sam a "stomach bomb" and food poisoning. Carly believes that all of these events were coincidences, refusing to think that Missy would ever hurt her friend, and convinced Sam that she was just being paranoid and thought that Sam was probably jealous. Carly tried to play peacemaker, and called them all together at the Groovy Smoothie to settle their differences. Missy and Sam apologized to each other, but once Carly left to buy smoothies, Missy showed her true colors and admits that Sam was right; she was trying to sabotage Sam and Carly's friendship so she could be Carly's only best friend. Missy knew Sam wouldn't retaliate in fear of losing Carly's friendship and used this to her advantage.Freddie won a contest for the six month School at Sea program but gave the trip away to Missy so she would stop interfering with Sam and Carly's relationship. To the excitement of getting to be on this cruise, Missy gloated about this to Sam, saying that it's no longer necessary to be Carly's best friend. However, Carly walked up behind her when she said this and realized that Sam was telling the truth. Carly stated that Sam is her only best friend and Missy told the girls to "enjoy each other" while she goes on her trip. Carly reveals to Freddie that Missy used to get really seasick when they were little and assumes that she doesn't anymore. The end scene shows that Missy is indeed still seasick, and the ocean liner she's on turns out to be a cargo ship.
- Haley Ramm and Miranda Cosgrove acted in the movie "Yours, Mine, and Ours" together, hinting at when the two actors first met.
- Haley and Miranda are best friends in real life to this day.
- Missy shows similar traits to Rebecca from Zoey 101.
- In "Boy Meets World", the character who came between Cory and Topanga was also named Missy Robinson.