Kalthoff gunsmiths

This family was founded was Herman Kolthoff from Kultenhof Estate, Danish Duchy of Slesvig (now Kaltenhof, Nordrhein-Westfalen, Germany), who had several sons that went on to fame across Europe. They are best known for the Kalthoff repeater - a rapid fire repeating rifle that could deliver 20-30 rounds/minute in the 1650s.
 * Peder Hermansen Kalthoff - Served Frederik III of Denmark as Head of Armory, 1600-1672
 * Matthias Kalthoff - Gunsmith Denmark, 1608-1681
 * Caspar Kalthoff Elder -- Served Charles I of England, 1606-1664
 * Caspar Kalthoff Younger -- Served Tsar Alexis I of Russia and Charles II of England
 * Henrick Hermansen Kolthoff -- Founded Foundries in Sweden and Norway, 1610-1661
 * William Hermansen Kalthoff -- Patented repeating gun in France

Descendants
The Kalthoff name spelling name was recorded as Kaldtoft, Kalthof, Kaltof, Kaltoft, Koldtoft according to local pronunciation and spelling habits. All of the families with these names in Scandinavia are descendants. (This remark is highly questionable and unreliable!)