Adalbert of Mainz, German archbishop
Adalbert I von Saarbrücken (died June 23, 1137) was Archbishop-Elector of Mainz from 1111 until his death. He played a key role in opposing Henry V, Holy Roman Emperor, thus securing the election of Lothair III rather than Henry V's chosen heir, causing later Holy Roman Emperors to make concessions in order to maintain hereditary monarchy.