Joseph Marcus was a Sydney convict who, when emancipated, became Australia's first unofficial Rabbi, before the creation of a synagogue. He was born in 1767 at Mannheim and received a religious education in Poland and Germany. He arrived as a convict in NSW in 1792, on a commuted death sentence. In the early 19th century, Marcus's congregation consisted of about 30 Sydney Jews. He died in 1828 in Sydney, and though buried as a Jew may have been converted by William Cowper.