Warner Bros. Games (in-universe)

WB Games, along with TT Games, appeared to have been the creators of LEGO Dimensions, as their logos were both featured on the box art and packaging for the game. (WC: Starter Pack Adventure)

Behind the scenes
Although not named in full in Starter Pack Adventure, the division of Warner Bros. shown in the webcast was known as Warner Bros. Games. As shown in-universe, they were indeed among the groups who created LEGO Dimensions.