Becky is a young girl who appears in the 2016 Sesame Street Christmas special, Once Upon a Sesame Street Christmas. She is one of the main characters of a bedtime story as told by Louie to Elmo to explain why it's tradition to leave cookies out for Santa Claus, taking place in a 19th Century version of Sesame Street. She is shown to be the daughter of the local constable (an ancestor of Mr. Johnson).
Becky is introduced when Elmo's ancestors move to the street and she claims his dropped basketball for her own. Elmo is quick to point out it's marked with an "E" for his name, but she asserts it's just a smudge, claiming her name is "Smudge." She is initially like the other residents of the street, unkind to everyone. But, she slowly learns to appreciate the Christmas spirit and Elmo's friendship. She eventually returns his ball as a Christmas gift, inspiring Elmo is spread kindness around the street to bring on the arrival of Santa.