Green’s Dictionary of Slang

important; snobbish, superior.

1938		D. Burley N.Y. Amsterdam News 27 Aug. A6: Weed smokers are due for the next big purge with the G-Men rounding up certain bigwig musicians.
1960		A. Buzo Front Room Boys Scene ix: I don’t kow-tow to any bloody bigwig nob.
2012		J. Díaz This Is How You Lose Her 3: I took her picture with some bigwig black playwrights.