Lizzie McDonald is a character from Life with Derek, played by Canadian actress Jordan Todosey. Life with Derek is a Canadian-produced show, which airs on Family in Canada, and on Disney Channel weekends in the U.S..
Lizzie McDonald is the sister of Casey, and daughter of Nora MacDonald-Venturi and Dennis MacDonald. Her new stepfather is George Venturi, her stepbrothers are Derek and Edwin Venturi, and her new stepsister is Marti Venturi.
Lizzie is an honest, decent, hardworking 12-year-old girl. She plays on the school soccer team, and has been injured playing that sport. She is known to be a tomboy, as when she is told this by Edwin in an episode where she has a crush on her soccer coach. She also takes Tae Kwon Do classes afterwards. Lizzie is some what of a naturist with her love of animals and concern for the rain forest (she is also an on / off again vegetarian). She used to go to school in Toronto with Casey until they moved in with the Venturis.
During Casey and Derek's many arguments, Lizzie has often been pulled in to aid Casey, and gotten the short end of the stick many times, like Edwin (and to a lesser extent, Marti) has to Derek. Like Edwin, they both love and admire their older siblings, but at times Lizzie and Edwin are used by their sister and brother, respectively. Although to her credit, she has a lot more backbone then Edwin. Also, it is Lizzie who on various occasions pulled the plug on Casey's and Derek's plans, while making Edwin see that Derek is being unfair towards him (though Edwin forgets this shortly after Casey and Derek stop arguing for the day).
Following this, Lizzie sometimes spends time with Edwin doing "science experiments." Their projects may either help with Casey and Derek's fighting or could result in supporting one of them. In the episode "Middle Man-ic", Edwin and Lizzie concluded that if Casey and Sam do not make up together, Derek's team will lose the hockey game and not go to Sweden (to meet girls). There was no conclusion to this experiment, but it is known that Derek will win the game, even though Sam and Casey break up in the end (and the destination of their trip is changed to Winnipeg, Manitoba). Basically, the projects they work on are based on psychology: The Human Life Form's Life. Their teamwork pays off, like Edwin giving sandwiches to Lizzie when George Venturi didn't pick them up from school. They also danced together in a party Derek threw. Lizzie is known to be very shy when it comes to her physical state. She also has a problem with dancing in one episode.
Lizzie and Derek get along quite well, and can be close when Casey isn't standing in the way. Derek doesn't tease her like Edwin or Casey, but doesn't love her like Marti. Derek once hugged her and called her "Super Lizzie," and he coached her in hockey when she was having trouble. He also considered himself her big brother, instead of her hockey coach or stepbrother. In one episode it is discovered that Lizzie changes her style to girly, being tired of wearing "clothes from the boys section".