Kate Pearson (born August 31, 1980) is Jack and Rebecca's daughter, Kevin's twin sister and former personal assistant who lives in Los Angeles, and Randall's adoptive sister. When Kevin decides to move to New York, he fires Kate in order to have her try to build her own life, apart from him. Kate is an ardent Pittsburgh Steelers fan and has a routine that she follows while watching every game. Kate had her appendix removed on Christmas Eve, when she was nine. She is morbidly obese and struggles with issues of self-esteem which she greatly attributes to her estranged mother. Kate's relationship with her mother led to depression and eventually led to her taking Prozac, which she needed to stop taking due to the weight gain. Kate decides that in order to lose weight she needs to join a support group. Kate, despite attempting to not get involved with anyone until she can get her weight problems under control, falls for Toby, whom she met in her support group. After struggling with her weight control for so long, Kate decides at Thanksgiving that she is going to have gastric bypass surgery. Before heading to New York for Thanksgiving, Kate breaks up with Toby, due to his inability to diet, thus being unable to support her. Toby surprises Kate, showing up at Randall's house for Christmas, stating that he can live without pizza and junk food, but he cannot live without her.


Mackenzie Hancsicsak (age 9) as the young, Kate Pearson.