megalomaniac

[ meg-uh-loh-mey-nee-ak ]

/ ˌmɛg ə loʊˈmeɪ niˌæk /

a person afflicted with megalomania.

Also meg·a·lo·ma·ni·a·cal

[meg-uh-loh-muh-nahy-uh-kuh l] /ˌmɛg ə loʊ məˈnaɪ ə kəl/, meg·a·lo·man·ic

[meg-uh-loh-man-ik] /ˌmɛg ə loʊˈmæn ɪk/. of, relating to, or suggesting megalomania or a person who is afflicted with it.

Origin of megalomaniac

First recorded in 1885–90; megalo- + maniac

And Downey is at his sarcastic, vulnerable, and megalomaniacal best in Iron Man 3.

‘Iron Man 3,’ Starring Robert Downey Jr., Is Loud, Quippy, Ridiculous Fun |Marlow Stern |May 1, 2013 |DAILY BEAST
She burns through staffers and appears to have a megalomaniacal sense of her own destiny.

Did Sexism Do Michele Bachmann In? |Michelle Goldberg |January 5, 2012 |DAILY BEAST
Spacey makes Abramoff an enormously appealing rage-filled, thieving, megalomaniacal sociopath.

Jack Abramoff's Redemption |Lloyd Grove |December 17, 2010 |DAILY BEAST
But Spacey makes Abramoff an enormously appealing, rage-filled, thieving, megalomaniacal sociopath.

Jack Abramoff's Redemption |Lloyd Grove |December 17, 2010 |DAILY BEAST

Initial paranoia, with megalomaniacal symptoms, on the basis of hereditary inferiority, with vicarious genius.

The Quest |Frederik van Eeden
He'd been a musical-comedy producer so long that no megalomaniacal absurdity could take him by surprise.

The Real Adventure |Henry Kitchell Webster