Hanna Marin is beautiful, popular, and thin, but things haven't always been this way for her. Formerly the chubby girl of the group, Hanna is now one of the most popular girls and certianly one of the mot materialistic. So materialistic that she is even caught shop-lifting. Her mother and father have recently divorced causing Hanna some turmoil to deal with at home. This only intensifies when she learns of her father's engagement to his new girlfriend- and her new step-sister Kate.

Hanna is very insecure due to her weight struggles. Her insecurities run so deep that when her boyfriend, Sean, refuses to lose his virginity before he's married she takes it personally. These feelings come to the surface when at a party Hanna trys to seduce Sean, but ends up getting denied once more. Hanna then left the party upset and took Sean's car. She ended up crashing his car and this leads to her working off the debt in Sean's mother's dentist office.

Before Alison's dissapearance, the two had a strainded friendship due to Alison's remarks about Hanna's weight. At one point in the show it is mentioned that Alison tried to help Hanna change her image, such as helping style Hanna's hair more like her own.