Surasa

Surasa is the mother of the Nagas and a member of the Council of Guardians.

History
When Hanuman was flying over the ocean on his way to Lanka to get Sita back to her husband, Rama, the gods decided to test him. Surasa appeared in the demigod's path in the form of a horrible rakshasi and said he was food brought to her from the gods. Hanuman explained the situation and promised to enter her mouth once he came back. But Surasa told him that he could pass only through her mouth, as per a boon given to her. So Hanuman challenged to open her mouth wide enough to eat him. He expanded his body and becoming larger while Surasa expanded her jaws so she could devour Hanuman. When Surasa's mouth was at one hundred yojanas (or fifteen hundred kilometers), Hanuman changed to the size of a thumb, flew into her mouth and out her ear. Impressed by Hanuman's ingenuity and courage, Surasa assumes her true form, explained that what did was merely a test from the gods, and blessed the demigod. Hanuman mentioned his encounter with Surasa to Rama after he returned from Lanka.

Aru Shah and the End of Time
Surasa's name was seen on one of the thrones of the Council of Guardians in the Court of the Sky.

Trivia

 * Some versions say that Hanuman went into Surasa's mouth and then quickly back out before she could close it.