No, it's Gay-Man

The "G" in G-Man from Half-Life 2 is widely believed to stand for "Government", as in "Government Man"—a term often used to describe mysterious federal agents in pop culture. This interpretation fits his original role in Half-Life, where he was conceived as a shady government administrator tied to Black Mesa.

However, Valve has never officially confirmed what the "G" stands for. Over time, the character evolved into something far more enigmatic: a "sinister interdimensional bureaucrat" with unclear allegiances and reality-bending powers. His name actually comes from his internal model file, simply labeled "gman".

So while "Government Man" is the most accepted theory, the truth is deliberately left vague—just like the G-Man himself.

GOVERNMENT MAN OR FBI, CIA. BUT MOSTLY FBI OR THAT'S MY UNDERSTANDING.