Mildred Finch (Kathy Najimy) bursts into Charlie Eppes' world in Season 3's "Waste Not" as the "Physics/Math/Astronomy division chair" - in other words, his boss from pretty much any angle. She wants more of Charlie's time to be put into "collaborative projects", limiting his opportunities to help his brother. As she simultaneously boosts Amita's career, Charlie is left uncertain of how he feels about her. His confusion only increases when "Millie" takes a shine to his visiting dad, and vice versa, particularly since Alan does not, in general, date.
She steamrollers "the Sean Connery of the Math Department", as she dubs Charlie, and is similarly a whirling dervish through the existence of Larry Fleinhardt, evicting him from his steam tunnel, but working hard to reintegrate him with the community at large. She appears in another eight episodes of Season 3, slowly insinuating herself into the lives of all three of "the Eppes ladies" as she refers to them when looking to get competition for a poker game. As Millie observes of Charlie, "you've made my life a little more difficult, and a lot more interesting", a backhanded compliment he is happy to return.
Millie disappears as suddenly as she came, but with far less fanfare - indeed into obscurity, and without reference.