The company founded by Ken and Roberta Williams, creators of the Quest series and many other games, until they were bought by Vivendi and became a publisher only.
Founded in 1980 as "On-line Systems", it was later renamed to "Sierra On-Line" and went on to create such classic series as King's Quest, Space Quest and Police Quest as well as Gabriel Knight and a number of other games. In addition to in-house development it also published games, which was eventually to become their sole activity. Existing now as a brand only, the last title to truly come from Sierra was Gabriel Knight 3.| Company Name | Sierra Entertainment, Inc. |
| Street Address | 6060 Center Drive, 5th Floor |
| City | Los Angeles |
| State | California |
| Country | United States |
| Website | http://www.sierra.com |
| Contact Email | |
| Phone Number | |
| Date Founded | Jan. 1, 1979 |
| Count of Games Published | 437 |
| Count of Games Developed | 146 |
| Aliases |
| Larry Laffer first in Leisure Suit Larry 1: In the Land of the Lounge Lizards | 25 |
| Roger Wilco first in Space Quest: The Sarien Encounter | 23 |
| Sonny Bonds first in Police Quest: In Pursuit of the Death Angel | 11 |
| King Graham first in King's Quest | 11 |
| Barney Calhoun first in Half-Life | 10 |
| Rosella | 10 |
| Gordon Freeman first in Half-Life | 10 |
| Crash Bandicoot first in Crash Bandicoot | 9 |
| Doctor Neo Cortex first in Crash Bandicoot | 9 |
| Coco Bandicoot first in Crash Bandicoot 2: Cortex Strikes Back | 9 |