Mary is seen in episode 70 at the house in episodes 71 and 72. She is seen at Red Lobster's and at a hotel w/ Harold Slikk.
Mary was known as Margarett Slikk before episode 6. Also, her birthday was known until episode 29 as 30th December. In episode 30, Harold says "You're 1970, not 1971, Mary!" In this series, she is voiced by Microsoft Anna. Her mother is Russian, stepfather German. Her real father (also Russian) died in 1979. She has got two sisters, Xenia and Veronika Unova. There is also a character called Yelena Unova, who was Vladimir Unova's mother. If she is friend or enemy with Catherine Randolf, is unknown. She is maybe enemy with Jake, William and Emilie. Mary works as a workwoman in this series (as Leopold wrote in episode 119).
Angela Mark's series
Mary is named Yelena Slikk and she hates when her husband Julian watches My Little Pony: Friendship is magic.
Mary is usually calm around her children, but hates Harold's guts, as she gets abused by him. She is seen in Episode 8 and Episode 9. She is voiced by Microsoft Mary.
Thomas Cartoon's series
Mary Slikk came here to visit the Slikk house. Leopold got so scared, he hides from her or she'll eat his brain but he decides to fight with her. After the fight, she got arrested for being a zombie
Mary Slikk has her same appearance, and she first appeared as the voice in Episode 17: AGK Cheats on his test, she ground Leopold when he cheats on his test, and she also first appeared as an actual appearance in Episode 58: AGK's Sore Throat, she gave Leopold some chicken soup to cure his sore throat.
Mary Slikk has her same appearance, and she first appeared in Episode 2, AGK vs. Sonic.exe.
In this series, she also appears rarely. She is calmer than Harold. She made her actual appearance in Episode 14 when Leopold and his family went on town to see the fireworks.
Unlike other AGK series, she has friends: Akako Otoko (Kaeru's mom), Michelle (Fabrice's mom), Rosemary Prower (Tailsko's mom), Linda Smallwood (Leon's mom) & Marge Simpson.
Also, instead of AGK high-pitched or MS Mary, she will be voiced by Millie Chicago (one of Fabrice's american cousins).
Tanzim K's series
In this series, she was called "Marie Slikk," which is a French and Czech variant of Mary. It is confirmed that in AGK EP20, she will be of Swiss descent.