That honor belonged to Nader Shah of Iran, who also took the peacock throne. Marathas were just like vultures and crows who scavenged by making life difficult for ordinary citizens of the Mughal Empire.
The British and their burnings of Lucknow, Agra, Dilli is what eventually brought the Mughal empire down.
Maratha's strength was in their lack of chivalry. They killed anyone to get what they wanted, men, women, children, elderly. They stole, pillaged, murdered, raped, and tortured innocents. They were also supported by the British themselves with advanced weaponry.
Internecine warfare among Mughal princes and the invasion of Nader Shah weakened the Mughals. The British, only then, were able to establish a foothold and expand further with the help of their proxies, Ranjit Singh and Marathas.
In other places, they made Muslim kings fight each other like the Nizam against the great Tipu Sultan.
All these groups became inadvertent proxies of the British empire.
The British observed how easily the Mughals wiped out the Portuguese navy which began attacking Mughal hajj ships. They knew they did not stand a chance against the full might of the great Mughals.