Mainly North American: from the name of a river in south-west Scotland that runs through Glasgow, perhaps by way of a surname derived from the river name, although for many Scottish emigrants it was the point of departure from Scotland. The given name gained some currency, especially in the American South. The bank robber Clyde Barrow became something of a cult figure after the film Bonnie and Clyde (1967), in which he was played by Warren Beatty.
English, French, Dutch, Slovenian, Croatian, and Jewish (Ashkenazic): from a Germanic personal name composed of the elements heri, hari ‘army’ + man ‘man’. As a Jewish surname this is no doubt an adoption of the German surname Hermann.