Gray Matter Studios

Not to be confused with Gray Matter or LTI Gray Matter.

Background
Gray Matter Studios was formed in 1999 by the original developer team of Xatrix Entertainment. It made two games and was picked up by Activision in 2002, and ultimately merged into Treyarch in 2005. Their last game, Call of Duty: Big Red One, was released under the Treyarch brand.

1st Logo (November 19, 2001)
Visuals: There is a round frame with the picture of a human brain from upward. The name is right to it, reading "gray" and "matter" below, and "STUDIOS" under it. It also has the words "and developed by" above, pointing to the fact that this logo actually comes after other logos.

Technique: Raining in the background.

Audio: The opening theme of the game.

Availability: Seen on Return to Castle Wolfenstein.

2nd Logo (September 14, 2004)
Visuals: We see parts of a human brain zooming to a light spot at the screen, while it flickers and shows noise. Then, the brain image flashes and the name appears, reading the same as before. Then the logo crashes.

Technique: The animation in the logo.

Audio: Whoosh sounds of the flying parts, flickering and other noise.

Availability: Seen on Call of Duty: United Offensive.