Since you're asking about the different roles (i.e. jobs) in the game industry, the Breaking In forum is the most appropriate place.

Read these to learn about the different roles in the game industry:

http://archives.igda.org/breakingin/career_paths.htm
http://www.sloperama.com/advice/lesson7.htm
http://lmgtfy.com/?q=different+roles+in+the+game+industry

The number of different roles and how many are each one can vary depending on the company. It isn't uncommon for only one person to be in charge of character design.

Amyrildora,

All the links that Tom posted are relevant, but I wanted to take a moment and answer the question directly.

First thing's first, as yaustar stated, the number of people filling each position in a game company will vary from company to company. With that said, all modern games share at least a passing similarity in their implementation, which creates a set of standard job duties.

First, game companies tend to break their company into a number of departments. These are, in no particular order:

* Engineering (aka Engieers & Programmers)
* Art (aka 2D & 3D Artists, 3D Modelers, Animators)
* Sound (Audio/Music Composition & FX; sometimes included in Art)
* Design (Writers, Level Builders, Game/Mechanics Designers)
* Production (Executive Producers, Sr. Producers, Producers, Associate Producers)
* IT (Network/Server Admin)
* Administration (Controllers, HR, Legal, Marketing, Office Managers, Quality of Life Managers, Secretaries, etc...)

Each department will have from 1 to N people, where N varies depending on the size of the company. For smaller companies there may be a single individual acting as both the HR Manager, as well as the Office Manager, as well as the Quality of Life Manager. While at a larger company there may be different people who fill each role.

In most companies the largest departments are Engineering and Art which can have as many as 15 people each on a single project. Smaller companies will have as few as 4-6 in each of those departments. Sound generally only requires 1-2, depending on whether the company wants an outstanding composer, a good SFX guy, or someone who's good at both.

The design department seems to vary the most from company to company. Many companies feel it's bad to have too many cooks in the kitchen and will thus limit the size of their design team intentionally. Others look at the large numbers of missions or maps than need to be built and ramp up half a dozen or more world builders, in addition to their usual writers and mechanics guys.

Production ranges from 1 to maybe 4 people on a project, depending on the size. Generally there will be 1 or 2 Associate Producers, a Producer or Sr. Producer, and then an Executive Producer. If the company is developing an application for a publisher, the publisher will also provide their own Producers to interact with the game developer.

IT will have from 1 to half a dozen depending on the size of the company. For large companies with over 200 seats, it can take many people to push software updates, monitor the security of the network, install new hardware as necessary, etc...

Within the individual departments, generally only 1 to 2 people will typically fill the same "role". For example, it's not uncommon to have a couple Graphics Programmers, but there is generally only 1 Sound, User Input, or IO Engineer. It all depends on the type of game being made, the amount of work to be done, and the quality and productivity of people who currently fills those roles. It's also about the philosophy of the company.

Some companies try and fill the company with specialized, extremely talented individuals in order to get as much productivity as possible out of someone in a single area, meanwhile other companies tend to hire more diverse, generalists. The former is often more efficient, but suffers from turnover problems, while the latter is less cost-effective, but reduces some risk involved in people leaving the studio, getting sick, etc...

Hopefully this all helps!