This has to take the prize for most misleading name in the annals of Forteana. While it gives the impression of a clerical, cassock-wearing phantom, this beast was nothing of the sort, being a "large rhesus monkey or a chimpanzee" that roamed the area between Latrobe and Ligonier in 1945.
The first real mention of the so-called 'monk' came on September 7, when an article appearing in the Altoona Mirror mentioned that the Reed School had been closed the day before due to sightings of the weird creature. It leapt into the midst of a corn roast being held at the school on the night of September 5, making off with two ears and displaying no fear of humankind. I'm assuming this was the incident which led to the closing of the school - as a local game warden (coincidentally also named Reed) said, "The parents won't let their children out of the house so long as the thing is on the loose. And we can't blame them." Reed had also been investigating the animal for a month, so presumably there's some earlier sightings, though I haven't seen them.
One of the witnesses to the animal was Paul Claycomb of Marietta, who said the 100-pound beast broke into his chicken house and stole one of the birds. His dog "almost broke down the door trying to get in the house when that thing came along."
Another article, appearing in the Indiana Evening Gazette the next day, reported another sighting of the beast, made the previous night. Two boys near Norvel, Norman White and Joseph Seville, were out in Seville's backyard with their dogs when they began to growl - swiveling their flashlights around the yard revealed the animal hiding nearby. One of the ubiquitous hunting parties was formed, but like practically every posse hunting a weird creature ever formed, all was for naught and they came up empty-handed.
And there the story seems to materialize and end. A predominant theory mentioned was that the ape escaped from a circus about six weeks before - isn't that the theory on any animal found where they aren't supposed to be?
This is probably the earliest sighting of a simian nature from the Chestnut Ridge I'm aware of, the Chestnut Ridge area of Westmoreland and Fayette counties being, apparently, the domain of Pennsylvania's resident Bigfoot population.
As a fun 'name game' aside, Wildcat Hollow might, or might not, be named after another weird creature - an article following up on the 1922 shooting of a long-tailed wildcat shot near Tinicum, Bucks county, says that the cats also inhabited the Chestnut Ridge.