Which spacecraft was the first to fly past Pluto?

New Horizons was the first spacecraft to fly past Pluto.

NASA launched New Horizons on 19 January 2006 from Cape Canaveral, Florida. It used a powerful Atlas V launch vehicle and a gravity assist from Jupiter in 2007 to increase its speed. The spacecraft made its closest approach to Pluto on 14 July 2015, travelling at about 14 kilometres per second relative to Pluto.

New Horizons sent back the first close images and scientific measurements of Pluto and its largest moon, Charon. Its observations revealed a varied world with mountains of water ice, broad plains of nitrogen ice and evidence of complex geological activity. Because a flyby is much faster than an orbiting mission, the spacecraft collected data during a brief encounter and transmitted it over many months.

New Horizons continued into the Kuiper Belt after Pluto. In 2019 it flew past the smaller Kuiper Belt object Arrokoth, then called 2014 MU69. Voyager 1 and Voyager 2 visited the outer planets, but neither passed Pluto, making New Horizons unique in this milestone.