
takes a bullet to the face
from a person or persons UNKNOWN.
Breaking Bad Season 4, Episode 7

"The image of the Professor was so UNKNOWN
Money Heist Season 1, Episode 8

whose UNKNOWN provenance
jeopardizes
The Big Bang Theory Season 5, Episode 2

I'm not comfortable
bringing in UNKNOWN entities
into our operation.
Breaking Bad Season 2, Episode 5

somewhere UNKNOWN.
And most likely...
Money Heist Season 3, Episode 2