Mosag was a female Acromantula, and the wife of Aragog. Sometime before 1993, Mosag gave birth to hundreds of baby acromantulas and co-founded the acromantula colony located in the Forbidden Forest near Hogwarts School of Witchcraft and Wizardry. Her husband died later in 1997. Their colony and descendants took part in the Battle of Hogwarts in 1998.
- "...and you see how our family has grown, all through Hagrid's goodness..."
- — Aragog[src]
Sometime before 1993, Mosag was born and found by Rubeus Hagrid. Hagrid already owned one acromantula, Aragog, who needed a wife to start a colony. Hagrid brought Mosag to the Forbidden Forest near the Hogwarts school grounds and the two reproduced and began a large colony of Acromantulas. These acromantulas quickly grew to form a large colony that would attack any fresh meat. It is likely that she, like Aragog, liked Hagrid, and ordered her sons and daughters not to attack him.
In 1997, Aragog died. Later, when Voldemort attacked Hogwarts castle during the Battle of Hogwarts in 1998, Aragog and Mosag's many sons and daughters were forced out of their habitat by Death Eaters, which made them enter the battle, attacking both sides.
- Mosag is a Scottish Gaelic word which means "dirty female" or "filthy" according to J. K. Rowling. A Dictionary of the Gaelic Language (Norman Macleod and Daniel Dewar, 1839) defines mosag as "a tawdry, drabbish woman; a worthless woman; a mean or avaricious woman."
Behind the scenes
- Mosag was only mentioned passively in Harry Potter and the Chamber of Secrets, and is not mentioned in the film version.
- It is unknown if Mosag fought in the Battle of Hogwarts. Because she never actually appears and is only briefly mentioned once, it is possible that she died sometime before Aragog. This seems likely, as she likely held the same respect for Hagrid as her husband, considering that Hagrid was responsible for her getting a mate to start a colony, and she likely would have stopped her children from attacking Hagrid if she were still around.
- Harry Potter and the Chamber of Secrets (First mentioned)
- Pottermore (Mentioned only)
- Wizarding World (Mentioned only)
- Harry Potter: Wizards Unite (Mentioned only)