Gianna "Gia" Martello is Abby's assistant choreographer. She is a performer, teacher and choreographer from Pittsburgh, Pennsylvania.
She started dancing at the age of four. Her raw talent and intensive training under the direction of Abby Lee Miller and the faculty at Reign Dance Productions earned her numerous titles as well as regional and national high score awards as a competition kid. At the age of 16, Gianna began choreographing routines alongside Ms. Miller as well as on her own which led her to discover her passion for teaching and choreography.
Her award-winning routines have earned her much recognition throughout the convention circuit. Gianna was able to balance her academic and dance opportunities with much success. Most recently, she graduated from Point Park University with a B.A. in Advertising and Public Relations, co-choreographed Alexx Calise’s, “Cry” music video and appears as the onscreen choreographer and cast member of Lifetime’s hit reality series, Dance Moms.
She has long brown hair and with lighter brown highlights on the bottom (some red) and blue eyes.
Earlier in Season 1, her hair was brown with blonde highlights, and also they were curly. In Season 2, they were fully brown.
In The Competition Begins, Gianna can be seen in the mirror while Abby is critiquing Paige on her performance during the rehearsal of the trio. She is later seen getting out of the van when she, the moms, and Abby arrive at the competition.
In Cathy Brings It On, and Melissa absent with her boyfriend, Abby explains that Maddie and Gianna have a close relationship, when Kelly is complaining of a lack of attention for her own daughters. Gianna's apparent reaction can be seen when Kelly yells that she does not need to buy Gianna gifts, because she is a "[expletive] teacher."
In Brooke's Turning Point, Gianna temporarily becomes the girls' only choreographer (replacing Abby), after Brooke leaves for cheerleading.
In Brooke's Back, Jill hires masseurs to give professional massages to Abby and Gianna.
Gianna is in the habit of tweeting "11:11" at identical times of the day. 
Gianna was Abby's student by the age of four or five.
She says the drama is real at the studio, and the drama was worse there when she was a dancer with "really crazy moms."
Gianna especially enjoys working with Maddie and Brooke, commenting that Brooke is very innovative and that its been stated many times throughout the series that she has a special working relationship with Maddie.
With Melissa away, Gianna took Maddie to video shoot for Alexx Calise's "Cry".
Her favorite solo she herself performed was "Look at Me" at age 15, one of Abby's first lyrical/contemporary pieces. Her favorite group dance she performed was "P.S. Take Care of My Baby," which received a perfect score at most of the competitions it was competed at.
Her second favorite show is Keeping Up with the Kardashians.
Everyone in her family danced (e.g., her mom, grandma, aunt, cousin.)