Roger Vacarius (1120-1200?) was an Italian authority in civil and Canon law, who became the first known teacher of Roman law in England. Apparently educated in Bologna, he was brought to Canterbury, possibly by Thomas Becket, to serve as counsel to the Archbishop of Canterbury Theobald of Bec, in his struggle with Henry of Blois, Bishop of Winchester. The case ended favorably for Theobald in 1146. It is to Vacarius that we owe most of the information that has come down to us about Speroni, a heretic from Piacenza.