In 1756, Johann Christoph Voigtlander founded and given his name to the Voigtlander optical company. Voigtlander is both the oldest name in cameras, and the most enduring. Between 1929 and 1956, Voigtlander produced a range of medium format folding cameras all called “Bessa”, another long-lived name.
In 1898 the Voigtlander company issued stock, and in 1925 Schering (a German pharmaceutical company) became the major shareholder. In 1956, Schering sold its shares to the Carl Zeiss Foundation, and Voigtlander and Zeiss integrated. In 1972 Zeiss / Voigtlander stopped producing cameras, and the Voigtlander brand was sold to Rollei. In 1982 Rollei collapsed and Plusfoto took over the name until selling it to Ringfoto in 1997.
Today, the German company Ringfoto is still producing Voigtlander branded cameras and lenses. Their 35mm rangefinder, and medium format models all use variants of the name Bessa (eg Bessa III W).
In 1999 Cosina leased the rights to the Voigtlander name from Ringfoto, and started to manufacture and market the Cosina Voigtlander brand. Today the unrelated Japanese company Cosina are also still producing Voigtlander branded cameras and lenses, and their models also use variants of the name Bessa (eg Bessa R2M).
Cosina's production of the Voigtlander, is not extraordinary: Cosina have long been a manufacturer of other's brands. These have included the Canon T60, Konica TC-X, Nikon FM-10 and FE-10, Olympus OM-10 and OM-2000, Pentax P 30T, plus the Yashica, FX-3 and FX-3 Super, to name but a few. In all, there are more than 100 cameras that have borne another manufacturer's name, but were made by Cosina.
But let's go back to Zeiss Ikon, a German company formed in 1926 by the merger of four camera makers, and one time owner of Voigtlander. Its other brands were Ikon and Contax; names others have bought to emulate.
Nippon Kogaku Kogyo Kabushikigaisha (Japan Optical Industries Corporation), or Nippon for short, was the company that found success with the Nikon SLR camera brand, but which started-out making copies of Contax rangefinder cameras. The name Nikon was claimed to be a merger of Nippon and Ikon, and it is reportedly reported that Zeiss filed a lawsuit alleging trademark violations of the brand name Ikon. I can not find evidence to support this rumor, but between 1963 and the early 1970s, all Nikon products sold in Germany were under the brand name “Nikkor”.
Bizarrely, in 1989, a year after Nippon had adopted the Company name Nikon, it sued the Ikon Photographic Corporation, a US manufacturer of inexpensive cameras, for trademark infringement, because Ikon was too similar to Nikon. Zeiss did not get in on the act because their US trademark had expired.
There is a similar rumor relating to Pentax. The company responsible for the Pentax brand was founded in 1919, and adopted the name Asahi Optical Company (Ltd) in 1938. There is much speculation about the etymology of the Pentax brand name, and some sources state Pentax was derived from a combination penta- prism and reflex. Others say it was a combination of penta-prism and “Contax”, a brand name of Zeiss.
Some commentators also claim the name Pentax was originally a registered trademark of Zeiss Ikon, and was licensed to Asahi Optical. However, other sources declare that all Germans patents were annulled following the country's defeat in WWII, and Asahi Optical were able to adopt the name without contest? Whatever the truth, the name Pentax does bear more than a passing resemblance to Contax.
Ziess (Carl Zeiss AG) absolutely leased the Contax name to the Japanese maker Yashica, and collaborated with them on the development a prestigious brand of 35mm cameras and interchangeable Yashica / Contax lenses. You remember Yashica; Cosina made their later cameras.
On the subject of Yashica, it's noticeable how many camera brands had names ending in “ca”. Fuji's brand name was Fujica, and there was also Bronica, Konica, Nicca and Praktica. “Ca” is supposedly a reference to camera, but all these names are remarkably similar to Leica (well about as similar as Nikon is to Ikon, and Pentax to Contax).
Getting back to Zeiss, the company had a bit of bother with its own name. At the end of WWII the organization was spit between Jena in West Germany, and Dresden in the East. As part of the World War II reparations, the Soviet army took most of Zeiss's tooling and stock back to the Soviet Union, leaving only the brand names behind. The western business became known as Carl Zeiss, while the eastern products became Zeiss Jena.
In conclusion, so far as camera names are concerned, Voigtlander started it, Zeiss claimed to own it, and Absolutely Cosina made it.