The first logo. First apperance on Half-Life.
Valve Corporation is an American video game developer and digital distributor, based in Bellevue, Washington, 1996 thru the present. Their first game, Half-Life, was highly acclaimed and since then they have made the Portal series, Left 4 Dead, and Counter Strike.
The second logo. First apperance on Half-Life 2: Episode 2
Info
This logo features the first Mr. Valve with a valve in one of his eye sockets looking at the viewer. First Apperance in Half-Life.
The second logo is a heavily-built man with a valve in the back of his head. First Apperance on Half-Life: Episode Two.
In Dota 2 and Portal 2, the same logo is used but but Mr. Valve will slowly turn his head towards the screen.
Scare Rank
Medium: The Man staring at you in a weird way could scare you a bit.
Medium to high: The Man looks even creepier than The 1st logo!
High to NIGHTMARE for the turning head variant.
The man now turning his head towards the camera is even creepier than the original logos!
Valve machine variant: None to low the Valve going onto the Man's head may scare some but those who are used to it none at all.
Fact.
The man from the 1st logo is a retired man from VALVE.
The 2nd logo. Is a randomly picked man from the street.
Valve Logo 1998-2013