Then a four-year-old stray picked up by former Prime Minister David Cameron from Battersea Dogs and Cats Home, Larry is now onto his third Prime Minister, Boris Johnson.
Officially known as the Chief Mouser to the Cabinet Office, Larry's duties include ridding number 10 of rodents, something he learnt to do during his time as a stray.
Other daily duties include greeting guests to the house, inspecting security defences and testing antique furniture for napping quality.
According to Larry's official description on the 10 Downing Street government page, he is also in the process of "contemplating a solution to the mouse occupancy of the house. Larry says this is still ‘in tactical planning stage’."
Larry isn't the only cat of Westminster, his neighbours include Palmerston, the Foreign Office cat; Gladstone, the Treasury cat; and Evie and Ossie, the Cabinet Office cats.
Several fights between Palmerston and Larry have broken out over the years, one particularly vicious scrap kicked off in 2016 resulting in Larry's collar being ripped off.
Click through the gallery above to see the 12-year-old tabby, Larry the Cat, in action.