Margaret Gilbert is the youngest daughter of Thomas and Elizabeth Gilbert, the niece of Judith and Robert Maxwell, the younger sister of Elena Gilbert. When her parents died, she was only a year old, therefore, she barely has any memory of them. Physically, she is described to have a strong physical resemblance to her elder sister Elena. She has white platinum blonde hair, very fair skin with peachy coloured cheeks, and light blue eyes.
In The Awakening, Damon threatened to bite Margaret when she was asleep because Elena would not come with Damon.
When Stefan goes missing, Elena becomes extremely depressed. She refuses anyone's company, but allowed Margaret to hug her. One day when Elena comes home, she finds Damon there. Margaret arrives with a tiny kitten that she names Snowball. Elena decides to introduce Snowball to Damon. The kitten scratches at him and runs away. To comfort a crying Margaret, Robert helps her find the kitten.
When Elena dies, her family is deeply saddened. Elena, a newly turned vampire, goes to visit her house and finds Margaret innocently sleeping in her bed. Snowball comes in and Elena notices she is showing signs that other dangerous animals are showing. Elena manages to scare the kitten away and get Margaret to invite her in the house. She talks to Margaret and tells her she is her guardian and will protect her. It is later revealed that Margaret's kitten was in fact Katherine von Swartzschild, the vampire who turned the Salvatore brothers. When the crazed animals attack the townspeople, Robert, Judith and Margaret are protected by Meredith and Matt.
- Margaret is a feminine name of Greek origin. The meaning of the name is "pearl" or "the child of the light".