Although this name is today found in the Iberian Peninsula, its probable origin is almost certainly 'Gallic', pre 5th Century. In the period of the 5th to 7th Centuries, the Gauls swept through France and what is now Spain and Portugal, before being defeated in 709 A.D.. The reminders of their occupation include many surnames. This one derives from the original leaders name 'Theodoric' (454 - 526 A.D.), and is more usually found in the Old French form of 'Thierri' or the post 1066 Norman invasion 'T(h)erry'. It is also found in the modern German as 'Thelscher' or 'Thielscher'. The name translates as 'People power', a logical name for a race which held Europe for over two centuries. The first recorded spelling of the family name is shown to be that of Ralfe Thesshere, which was dated September 3rd 1598 married at St. Brides Church, Fleet Street, London. during the reign of Queen Elizabeth 1, 'Good Queen Bess', 1558 - 1603. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.