Saturday Night Live
As a "featured player," Kristen's first appearance was November 12, 2005 in the sketch "Soaking Wet Killer" with Jason Lee and Jason Sudeikeis. She became a full cast member the following year.
If a video is available on the site, you will see 
next to the sketch.
Each sketch page has the original air date, the host, and a short summary.
Characters
Her recurring and some one-shot characters
Impressions
Celebrities and other individuals Kristen's done impressions of
Sketches
Comprehensive list of every skit Kristen's appeared in
Commercials
SNL's fake commercials with Kristen
Dress Show Edits
Sketches with Kristen that were performed at dress rehearsals and cut from the live shows
Sketch dates are taken with thanks from The SNL Archive and sketch titles come from Official SNL site, and dress show edits come with thanks to Jamie
