Viewers of the the iCarly movie "iFight Shelby Marx" are no doubt wondering, "Who is Shelby Marx?" It turns out she's not a real person or a martial arts fighter, but a character played by the 16-year-old actress Victoria Justice (see her official Web site below). 

If Shelby Marx looked familiar during the iCarly special, it's probably because she's been around teen and children's TV shows for a while. She was a regular on the show "Zoey 101," playing the character of Lola Martinez. She was in one episode each of "Everwood" (in 2006), "The Suite Life of Zack and Cody" (2005), and "Gilmore Girls" (2003). 

For more on her appearances in film and television, check out the Victoria Justice IMDB page.