Mladen, Irina
Planetary wizard for Earth during the period beginning with SYWTBAW through AWOM (and additionally in GWP). Like many other Planetaries, Irina is a geomancer.
Irina's exact age is unknown, though Nita thinks of her as looking "like a young housewife" when the Earth's most senior wizard turns up with her baby (and a parakeet) on Gili Motang, so she may possibly be in her late twenties or early thirties. Irina is Slovenian; she lives in Jelovec, a small town near the capital city of Maribor, where she works as a computer programmer and IT specialist. Her entry in the Manual suggests that she is both one of the youngest and one of the most powerful Planetaries to work on Earth in decades, having accepted the position just after graduating from university in Vienna.
Irina has been Earth's Planetary wizard for the entire period covered by the Young Wizards series: she is first referred to in passing in SYWTBAW by Tom and Carl. She does not appear "on stage," however, until the events of AWOM require her intervention in the events surrounding the potential awakening of the Martians in AWOM. She (and her baby) appear once early in the story to visit Mamvish and travel with her (and the group including Nita and Kit) to Mars to do an evaluation of the newly-found Superegg; and then again later when events escalate sufficiently to threaten all of Earth directly -- at which point Irina arrives in her capacity as Earth's Planetary to mediate the situation.
In AWOM, Mamvish remarks to Nita and Kit that if the Powers that Be needed the Earth destroyed, Irina would be the one they'd turn to. She also suggests that Irina may either directly control the Earth's kernel, or sometimes actually contain it.