Adrie "Aalt" Mondria (born 9 May 1956 – 2011), named Aalt M. in the media, was a Dutch criminal and serial killer who committed four murders and was responsible for a large number of assaults. Mondria was considered extremely violent and aggressive. After a notorious murder of his girlfriend's 10-year-old son, he was sentenced to 18 years imprisonment in 1998, after initially receiving life imprisonment for three murders in 1978, for which he also received 15 years imprisonment.