Glass or Glaß is a surname with several sources.
It can be Cornish, English, German, Russian/Slavic, Irish or Scottish.
Many with the last name Glass, are of eastern European descent, where Glass is a shortened version of their original last name.
It is also a Jewish surname, adopted by some Eastern European Ashkenazi in the nineteenth century.
[1] After being forced by the authorities to take on a surname, Jews in this area typically chose names referring to places, animals, occupations or signifying personal traits.