One of the most revered names in cameras and lenses. Their history runs long and meandering.
Founded in 1756, "Voigtlander" is the oldest name in cameras. Although the name has been preserved, the company has changed quite a bit over the years. In 1956 is was sold to Zeiss, then Zeiss sold it to Rollei, then it went to Plusfoto, then Ringfoto... finally in 1999 the name went to Cosina, a Japanese company that now produces some Zeiss and Voigtlander branded lenses (as well as others).
For dSLR owners, the current Zeiss and Voigtlander offerings are outstanding. Old world build quality and exceptional image question. Some verging on affordable as well!
The Wikipedia page for Voigtlander is very good.