Alexander Borisovich Beider (Russian: Александр Борисович Бейдер, IPA: [ɐlʲɪkˈsandr bɐˈrʲisəvʲɪdʑ ˈbejdʲɪr]; Yiddish: אלכסנדר ביידער, IPA: [alɛkˈsandər ˈbɛɪdər]) is the author of reference books in the field of Jewish onomastics and the linguistic history of Yiddish.