Which publisher releases the Paper Mario series?

Nintendo publishes the Paper Mario series.

The games are developed primarily by Intelligent Systems, but Nintendo owns the Mario franchise, oversees the series, and releases the finished titles. This makes Nintendo the publisher rather than a developer such as Intelligent Systems or a company associated with an earlier Mario RPG.

The series began with Paper Mario, released for Nintendo 64 in Japan in 2000 and internationally in 2001. It originated partly from development ideas for a follow-up to Super Mario RPG, but the project became a separate Nintendo 64 game with its distinctive paper-inspired presentation.

A frequent mix-up is Square Enix, because Square developed Super Mario RPG for the Super Nintendo Entertainment System. Square did not publish the Paper Mario series. Intelligent Systems developed the original Paper Mario and most main entries, while AlphaDream developed the Mario & Luigi: Paper Jam crossover. Those developer distinctions do not change the series-wide publisher: Nintendo.