Petrus or Pieter van der Aa (1530 – 1594), also called Vanderanus, was a Brabantine jurist.
His father, Johan van der Aa, was a descendant of a well-known Brabantine family of patricians, which had settled in Leuven, Mechelen and Antwerp.
While his biographers disagree on some events in his life, it is considered that Petrus studied in Leuven and achieved his Doctor iuris utriusque in 1559.
Three years later he was given a professorship in the same town, when his predecessor, Johannes Tack, moved to Douai in France.
Petrus van der Aa acquired the title eques auratus (Knight of the Golden Spur) on 30 October 1583.