When I do this I am ignoring: 1. indie studios (Shantae would be here otherwise), 2. companies that only work on one franchise (Red would be here otherwise), and 3. characters who do not have their own games (such as the Neversoft Eyeball or Johnny Turbo)
The criteria a character needs to meet is that they represent the company as a whole in marketing, not just their own games.
- Mario (Nintendo)
- Sonic (Sega)
- Pac-Man (Namco)
- Astro Bot (Sony, Worldwide)
- Toro Inoue (Sony, Japan)
- Space Invaders (Taito)
- Crash Bandicoot (formerly, Sony, under license from Universal)
- Gex (formerly, Crystal Dynamics)
- Aero the Acro-Bat (formerly, Sunsoft, probably US only?)
I also want to give a borderline mention to the Rabbids - they've popped up in a lot of Ubisoft games, kinda like Hidden Mickeys, but don't really promote Ubisoft as a wider brand.
Everyone else who's described as a mascot either just got labelled that because they're a cartoon (Bubsy, Bentley Bear, Rayman, Mega Man) or simply for being the most popular game the company has made at the time (Alex Kidd, Master Chief, Kratos)