K series may refer to:
- Lincoln K series, a line of luxury vehicle
- Scania K series, a series of bus chassis with longitudinal rear-mounted engines
- Skoda K series, a heavy howitzer
- K series engine (disambiguation)
- International Harvester K and KB series, a line of heavy trucks of the 1940s
- QI (K series), the eleventh series of quiz show QI
- Sony Ericsson K series, a series of cell phones
- K-series (trains), a type of train in China
- "K" series, a set of messages in the military Variable Message Format data protocol
- K Series (TV series), a television programming block on Puthuyugam TV
- K Series, a series of bullion coins produced by Korea Minting and Security Printing Corporation