* Main Cast: 12
* Recurring Characters: 10-15 (depending on how you define recurring)
* Guest Stars: Many, with some appearing in multiple episodes
So, you could say there are roughly 20-25 main and recurring characters in Season 3. However, it's worth noting that:
* Some characters have very limited roles and may not be considered "major" by some fans.
* The show also introduces new characters throughout the season, and some previous characters graduate or leave New Directions.
Therefore, it's impossible to give a precise number for all Glee characters in Season 3.