Destroyer of Worlds is a novel set in the Known Space series, by Larry Niven and Edward M. Lerner? published in 2009. It is a sequel to their previous novels, Fleet of Worlds and Juggler of Worlds. It is set ten years after Juggler of Worlds, drawing heavily from Protector, but, like the rest of the series, can sit as a stand-alone. It was followed by two other novels, Betrayer of Worlds (2010) and Fate of Worlds (2012).
The plot involves New Terra? and the Puppeteers (and the Gw'oth) entering into conflict with a Pak Protector fleet (though not the fleets featured in Protector). It also resolves why Alice Jordan's knowledge about the Pak never entered later novels, and restates the known timeline of the Home conversion to a planet of protectors.