The fifth season of the American television comedy The Office premiered in the United States in the 2008–2009 television season on NBC on September 25, 2008 and concluded on May 14, 2009. The fifth season consisted of 28 half-hours of material, divided into 24 half-hour episodes and two hour-long episodes. The Office is an American adaptation of the British TV series, and is presented in a mockumentary format, portraying the daily lives of office employees in the Scranton, Pennsylvania branch of the fictitious Dunder Mifflin Paper Company. The season stars Steve Carell, Rainn Wilson, John Krasinski, Jenna Fischer, and B. J. Novak, with supporting performances from Ed Helms, Melora Hardin, Leslie David Baker, Brian Baumgartner, Creed Bratton, Kate Flannery, Mindy Kaling, Angela Kinsey, Paul Lieberstein, Oscar Nunez, Craig Robinson, and Phyllis Smith.

The Office is an American mockumentary sitcom television series based on the 2001–2003 BBC series of the same name created by Ricky Gervais and Stephen Merchant. Adapted for American television by Greg Daniels, a veteran writer for Saturday Night Live, King of the Hill, and The Simpsons, the show depicts the everyday work lives of office employees at the Scranton, Pennsylvania, branch of the fictional Dunder Mifflin Paper Company, and aired on NBC from March 24, 2005, to May 16, 2013, with a total of nine seasons consisting of 201 episodes. The show was co-produced by Daniels' Deedle-Dee Productions and Reveille Productions, in association with Universal Television. The original executive producers were Daniels, Gervais, Merchant, Howard Klein and Ben Silverman, with numerous others being promoted in later seasons.