Tony Hawk's Pro Skater 5 was the first new main-series game since which 2007 title?

Tony Hawk's Pro Skater 5 was the first new main-series game since 2007's Tony Hawk's Proving Ground.

Proving Ground was released in 2007 and became the ninth main installment in the franchise. It was developed primarily by Neversoft, with different studios handling versions for systems including the PlayStation 3, Xbox 360, PlayStation 2, Wii and Nintendo DS. It was also Neversoft's final Tony Hawk game before the series moved to Robomodo.

After Proving Ground, the franchise went through a period of spin-offs and experiments, including the peripheral-based Tony Hawk: Ride and Tony Hawk: Shred, plus the compilation-style Pro Skater HD. The traditional main series then returned with Pro Skater 5 in 2015.

Project 8 is the main source of confusion because it was another major pre-Proving Ground entry, released in 2006. Underground 2 and American Wasteland were earlier still, so none of those titles fits the question's 2007 date.