Used pejoratively, the term "Rembrandt" can be applied to any lecherous individual over 40 with pedophilic predilections of any sort.
The term was originated in Germany in the early 2000s in reference to a highly suspicious park-dweller in Bonn who accosted a group of schoolchildren inviting them to a "night walk" with lanterns. The individual wore an ornate leather hat not unlike those in Rembrandt's famous painting "The Night Watchman."
The term can also be used more playfully to designate any individual (almost always male) guilty of ogling women under 18.