Which spacecraft first returned close-up images of Mars?

Mariner 4 first returned close-up images of Mars.

NASA launched Mariner 4 on November 28, 1964, and the spacecraft flew past Mars on July 14, 1965. It transmitted 22 television images, covering only a small portion of the planet but providing humanity’s first close-up views of another planet.

The photographs showed a cratered, Moon-like surface in the regions observed. They challenged popular expectations that Mars might have canals, lush vegetation, or an Earth-like environment. Mariner 4 also gathered measurements of the Martian atmosphere and magnetic environment.

Mariner 4 was a flyby spacecraft, not a Mars orbiter or lander. Mariner 9 later became the first spacecraft to orbit Mars, while Viking 1 became the first successful long-duration lander.