BTH

Before the Helmet (a photo series on StarWars.com)
Found on http://www.swbookzone.com/glossary.html

BTH

Beyond The Horizon
Found on http://www.tornado-data.com/siteinfo/glossary.htm

BTH

British Thomson Houston former electric traction equipment supplier
Found on http://www.encyclo.co.uk/local/21542
No exact match found