William Albert Wagenaar was a Dutch psychologist noted for his work on the reliability of memory.
He gained fame as an expert witness in some high-profile legal cases.
Wagenaar was called as an expert witness at a series of high-profile cases. These included the trial of John Demjanjuk who was accused of being the Nazi war criminal known as Ivan the Terrible. Wagenaar was also an expert in the a much publicised Dutch incest case (The Yolanda B case). In these cases his testimony focused on the reliability or otherwise of eye witness memory