"Birth" (2004)
Badly received and much misunderstood at the time, "Birth" has grown in reputation as the years have gone on, and it now reveals itself as, if not Kidman's very best performance, than certainly in the top rank. In Jonathan Glazer's firmly original film, she plays Anna, a privileged New Yorker about to remarry, ten years after the death of her husband. At a party for her mother, she's confronted with a young boy, Sean, who claims to be the reincarnation of her dead spouse. A bold, brave, extraordinary and unique picture that never goes where you expect it to go, it's one of the great unsung pictures of the last decade. And Kidman is wondrous in it, as Anna navigates old wounds reopened by this unsettling young upstart; she's angry, vulnerable and increasingly won over, and even turned on (an incredibly brave choice to take) by the possibility that her true love has returned. It's a beaut of a part, and Kidman plays every note like it's the last role she'd ever play, right down to the genuinely surprising (if perhaps a little too neat) third act twist. If you've never seen it, rush and find it as soon as you can, if only for Kidman's face in the breathtaking, wordless opera sequence.

Margot At The Wedding

"Margot At The Wedding" (2007)
One of Kidman's great virtues (and perhaps something that's kept her from really excelling in more straight-up romantic fare like "Australia") is her lack of need to be loved by the audience, and that's never been clearer than in Noah Baumbach's "Margot at the Wedding." Another film somewhat undervalued at the time (and it is admittedly a step down from the sheer brilliance of the director's previous film, "The Squid and the Whale"), it sees Kidman play the titular Margot, a self-absorbed, petulant author who blows into a seaside town like a hurricane for the wedding of her sister Pauline (Jennifer Jason Leigh) to Malcolm (Jack Black), with designs on an old flame (Ciarán Hinds) who's hosting a Q&A in a local bookshop. More than any other film on this list, you feel that Kidman's simply having a blast in the part, revelling not just in the chance to play such a terrible fucking human being, but also in the relatively rare occasion that she doesn't have to carry an entire film on her shoulders, with Leigh and Black each giving impressive turns too. We understand entirely why people find it a difficult film to love, but you're missing out on one of Kidman's most acerbically funny turns (and her sense of humor is one of her more underrated tools) if you avoid it.

Rabbit Hole

"Rabbit Hole" (2010)
Unlike "Birth" or 'Margot,' Nicole Kidman was given serious recognition, including an Oscar nomination, for "Rabbit Hole," and yet the film still managed to elude audiences. Which once again is a great shame. It's got a degree in common with "Birth," in that Kidman plays a woman haunted by grief who finds solace in a friendship with a much younger boy. In this case, however, she's part of a married couple, alongside Aaron Eckhart, whose 4-year-old son chased his dog into the road and was killed by a teenager (Miles Telller). Becca, Kidman's character, is so overwhelmed by grief that she simply wants to wipe the slate clean, getting rid of her child's possessions and moving away, and her quiet fury is impressive, matched by lovely moments of serenity. And it's one of the more moving portrayals of life going on after grief -- the couple are trying to struggle on, and almost find themselves forgetting their troubles for a second, which is how it actually happens. The film doesn't quite overcome some of the issues of David Lindsay Abaire's source play, or the essential staginess of that material, but Kidman (and Eckhart, who didn't get the same plaudits, but should have) is a wonder.