Origin of this VERY weird surname!

[Sikeliot]

"Mnookin"

What the heck could it be? The person who has this name that I am thinking of, looks West Asian.

[Sikeliot]

My best guess would be Armenian and that it was originally "Manoogian"

[Gustave H]

My best guess would be Armenian and that it was originally "Manoogian"

Why the hell would someone change their surname from Manoogian to Mnookin?

[Sikeliot]

I don't know, but what else could it be? Sometimes when people came over here, their names were improperly transcribed at Ellis Island.

[oh-nahhh]

Jewish would be my educated guess.

[Sikeliot]

Jewish would be my educated guess.

Jewish surnames don't exist unless you mean Hebrew. Ashkenazi surnames have a Germanic or Slavic basis, Sephardi have a Latin one.

[Linebacker]

Eastern European probably.

Like Example - Boris Mnookin

[Ouistreham]

Russian Jewish surname.

Found also in France under various spellings, like Mnouchkine.

See for instance Parisian stage director Ariane Mnouchkine, whose Jewish father was an immigrant from Saint-Petersburg, Russia:
https://en.wikipedia.org/wiki/Ariane_Mnouchkine