The much-loved eight-year-old peacock – a familiar sight to visitors to the abbey – was mauled by the animal at 7am on Sunday, June 20.
Tragically his injuries were so severe he had to be put down by a vet following the savage attack.
The beautiful and exotic creature was named after 28-year-old Arthur Parkinson, a former apprentice at the Nottingham City Council-run Newstead, who raised him from an egg.
Devastated Arthur posted on Instagram: “Very sad to learn that a peacock named after me was killed at Newstead Abbey over the weekend due to a dog being off its lead.
"The owner just walked away leaving the injured bird to be found by staff. Sadly the attack saw Arthur having to be put to sleep.
"Keep dogs under control, train them, there isn’t a law that says you have to have a dog – it’s a choice with that comes responsibility.”
Arthur the peacock became popular with visitors and staff and was often seen around the courtyard cafe area.
The incident happened despite signs at the historic site – the former home of Lord Byron – warning people to keep their dogs on leads.
Abbey site manager Mick Smurthwaite said: “Newstead Abbey and Park is home to a wonderful array of wildlife, including our most famous residents, the peacocks.
“Sadly, one of our much-loved peacocks, Arthur, was attacked by a dog off the lead at the weekend.
"Unfortunately, after being assessed by a vet, he had to be put down because of the extent of his injuries. Arthur will be sadly missed by us all.
“This serves as a stark reminder of the importance of keeping dogs on leads when visiting the park for the safety of our wildlife and visitors. We’re working with the RSPCA to appeal for information about this incident."
Peacocks were introduced to Newstead by the Wildman family around 200 years ago and have since been much loved by visitors and staff.
Lord Byron was an admirer of exotic animals and kept pet peacocks during his time in Italy.
The attack has also led to a warning from RSPCA officials urging dog owners to keep their pets on a lead.
Insp Keith Ellis said: “This is such a tragedy and one that could have been so easily avoided had the dog owner kept their dog on a lead.
“We ask that dog owners be aware that there may be wild animals present in the area when walking their dog and to keep their dog under control at all times.
“I would like to speak to the dog owner regarding this incident and would urge them or anyone who has any information regarding this to contact me on the RSPCA inspector appeal line on 0300 123 8018.
"We hope that what happened to poor Arthur will remind people of the dangers dogs can pose to wildlife when not kept on the lead.”