Wednesday is originally a pale, dark-haired, grim-looking little girl with a fascination with death and the macabre. She is explicitly stated to be six years old in the series' pilot episode. In the 1960s Television series, she is significantly more sweet-natured, although her favorite hobby is raising spiders; She is also a ballerina. Wednesday's favorite toy is her Marie Antoinette doll, which her brother guillotined. In one episode, she is shown to have several other headless dolls as well. She also paints pictures (including a picture of trees with human heads) and once writes a poem dedicated to her favorite pet spider, Homer. Wednesday is deceptively strong; she is able to bring her father down with a judo hold.
Wednesday had a close kinship with the family's giant butler Lurch. In the TV series, it was revealed that her middle name is "Friday". In the Spanish language version, her name is Merlina Addams (Latin America) or Miércoles Addams (Spain). In the Brazilian version (Portuguese), her name is Wandinha.