Quentin V. Manderbill is the villain of the Danger Rangers episode "Where the Fun Never Stops." He is a duck and mad scientist. He had previously won a Nobel Prize at the age of 10.
Quentin insists on being referred to simply by his first name because "Mr. Manderbill" is his old drake (father). He doesn't care about any playground or child.
Quentin's villainy is that he has rigged playground equipment with prizes, making sure children have to get in serious danger to try to get the prize (which, not to mention, takes away their sight of the true reason to play on playgrounds). He uses the wasted energy of the children to power his machine. In the process, anytime a Danger Ranger inspects, he kidnaps him or her, and the same eventually goes for Ranger Sully as he searches. He keeps them trapped in force fields. Fortunately, this does not include Ranger Gabriela (as she has been at headquarters monitoring the rest of the rangers until the force field has made them lose contact with each other and Savo).
As soon as Ranger Kitty picks up the phone with her tail and calls Gabriela to tell the Junior Danger Rangers to stop every kid from playing on the playground equipment, this ends up freeing the captive rangers, much to his dismay. He runs to ruin the playgrounds again, but the Rangers chase after him. Burt even uses an invention. Eventually, he is trapped in a merry-go-round and arrested by the police.
Quentin is voiced by Rob Paulsen (primarily the voice of Ranger Squeaky).