Rollei (German pronunciation: [ˈʁɔlaɪ]) was a German manufacturer of optical instruments founded in 1920 by Paul Franke and Reinhold Heidecke in Braunschweig, Lower Saxony, and maker of the Rolleiflex and Rolleicord series of cameras. Later products included specialty and nostalgic type films for the photo hobbyist market.

Originally named Werkstatt für Feinmechanik und Optik, Franke & Heidecke, the company renamed into Rollei-Werke Franke & Heidecke GmbH in 1972, Rollei-Werke Franke & Heidecke GmbH & Co. KG, in 1979, and Rollei Fototechnic GmbH & Co. KG in 1981.

After being purchased in 1995 by Samsung Techwin, part of the South Korean Samsung Group, it was sold back to its internal management in 1999. In 2002, it was bought by a Danish investment group, and renamed Rollei GmbH in 2004.

In 2005/2006, the company headquarters moved to Berlin and the company was split into two different companies: Rollei GmbH in Berlin, owner of the Rollei brand and selling various OEM equipment, and Rollei Produktion GmbH in Braunschweig, an equipment factory which became Franke & Heidecke GmbH, Feinmechanik und Optik.

Following another restructuring in 2007, Rollei was split into three companies. Franke & Heidecke GmbH, Feinmechanik und Optik focused on the production of professional medium format cameras and slide projectors, while RCP-Technik GmbH & Co. KG in Hamburg was responsible for Rollei consumer products like re-branded compact digital cameras in the European market, and with the RCP Technik Verwaltungs GmbH owning the rights to the "Rollei" and "Rolleiflex" brands. Finally, Rollei Metric GmbH took over the photogrammetry business.

In early 2009, Franke & Heidecke GmbH, Feinmechanik und Optik declared itself insolvent. Since 2009 Rolleiflex medium format cameras, Rollei 35 and Rolleivision slide projectors were being produced by the DHW Fototechnik GmbH—a company founded by Rolf Daus, Hans Hartje and Frank Will, former Franke & Heidecke employees. DHW Fototechnik presented two new Rolleiflex cameras and a new electronic shutter at photokina 2012. DHW itself filed for insolvency on 2014–08–15 and was dissolved in April 2015, thereby temporarily ending any further production of cameras, lenses and accessories. A new, smaller company called DW Photo was formed with reduced staffing, and more or less the same people leading the business; the manufacturing and sale of projectors and twin-lens reflex cameras, as well as that of the series 6000, was stopped, to concentrate on the Hy6 and accessories. A new battery and charger for owners of the 6000 series were however released to the market in 2019, as the original NiCd batteries could age prematurely.

As of 2015 the brands "Rollei" and "Rolleiflex" continue to be owned by the RCP Technik Verwaltungs GmbH. On 2015-01-01, the RCP-Technik GmbH & Co. KG refirmed as Rollei GmbH & Co. KG to market digital consumer cameras and accessories under the "Rollei" label in Europe.