Which company developed the original Tony Hawk's Pro Skater?

Neversoft developed the original Tony Hawk's Pro Skater. The California studio had not previously specialized in sports games, but its technical work and willingness to prioritize enjoyable skating convinced Activision to hand it the project.

Before Tony Hawk became the face of the franchise, Activision was exploring the growing market for skateboarding games. Neversoft initially experimented with a concept influenced by Sega's arcade game Top Skater, but moved away from its race-focused structure toward freer levels built around tricks, goals, ramps, rails, and combo lines.

The game used a modified version of Neversoft's Apocalypse engine, and the team studied real skateboarding while designing its physics and animations. Tony Hawk joined the project during development, lending his name, likeness, and expertise. Activision published the finished game in 1999, and its success led to Neversoft developing the main Tony Hawk titles through 2007.

Rockstar and Electronic Arts were not the original developer, while Activision was the publisher. That developer-publisher distinction is the common source of confusion in this question. Activision acquired Neversoft in 1999, shortly after the game's release.