The Queen star was the guest host on Saturday's episode, which celebrated the actress' busty figure in a series of risqué sketches.
Mirren's opening monologue saw her serenaded by SNL's male regulars in a modified version of There's Nothing Like a Dame from the musical South Pacific, during which they claimed she was "exactly like the Queen", prompting the actress to quip, "Have you ever seen Caligula? I'm in the orgy scene!"
Her breasts became the central point in another segment about her magical bosom as she was groped by comedienne Nasim Pedrad, while Kristen Wiig stuck her face in between Mirren's boobs to demonstrate its healing power.
The episode also saw the 65 year old spoof Helena Bonham Carter alongside Bill Hader as her director husband Tim Burton, and she portrayed Julie Andrews as a Cockney-speaking demanding diva during a talk show segment with Andy Samberg as Hugh Jackman.
But Mirren drew the biggest laughs as former First Lady Eleanor Roosevelt in a sketch which panned Katie Holmes' poorly-received historical program The Kennedys.
The skit began with a fake trailer for the TV mini-series, with the voiceover stating it as, "A series critics call 'rife with historical inaccuracy', 'complete fiction' and 'sucky'."
Mirren and Hader went on to star in an advertisement for new series The Roosevelts, and the actress, as Eleanor, shared a lingering kiss with a sultry Monroe, played by Abby Elliott.
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