This half-metre long rat was found by astonished home owners after it was caught nibbling on dog food in their shed in Penryn.
Kirstie Rollason's father-in-law put down traps to capture the cheeky critter who kept burrowing into sacks of food he kept outside for black labrador Sasha.
Expecting to find a little mouse, he was astonished when he caught this huge rodent measuring a terrifying 50cm from nose to tail at his bungalow in Penryn.
Kirstie, 41, a teaching assistant, said: "They knew they had rats, but had no idea it was this size.
"My father-in-law couldn't believe it - he just thought 'bloody hell'. He had never seen anything like it.
"They live right by the Penryn River so I think that might have been where it came from.
"The dog was very afraid of it - she was cowering away when she say it.
"You can tell how big it is because that is my father-in-law holding it and he is 6'1".
"Thankfully it was a one off - we haven't seen anymore."