Endeavour is an impact crater located in the Meridiani Planum extraterrestrial plain within the Margaritifer Sinus quadrangle (MC-19) region of the planet Mars. Endeavour is about 22 kilometers (14 mi) in diameter. Using Mars Reconnaissance Orbiter data, phyllosilicate-bearing outcrops have been detected along its rim. These minerals may have formed under wet conditions in a low-acidic environment during the early history of Mars. There are raised rim segments to the north, east, and southwest. The rim has become worn, rounded and degraded, with infilling of plains material in a manner similar to the Victoria crater.

When compared to the surrounding plains, the crater floor shows an enhanced spectral signature of basalt and hematite. The interior contains two groups of dune fields. Images taken since 2008 show evidence of changes in some of the associated formations, which may be evidence of active erosion by the martian wind over a period of two to three years. The plains surrounding the rim show evidence of polyhydrated sulfate.

The Mars Exploration Rover-B Opportunity began travelling toward this crater in August 2008, with the rim coming into sight on March 7, 2009, and arriving at the edge on August 9, 2011.

Endeavour averages about 200 to 300 metres (660 to 980 ft) deep, with an area in its southeast that goes down to 500 metres (1,600 ft) deep, according to a publication called Degradation of Endeavour Crater, Mars by the Smithsonian Institution. The south-west depression goes down to an elevation of −1,980 metres (−6,500 ft), the horse-shoe shaped depression sits in the south-east quadrant and is around minus −1,800 to −1,900 metres (−5,900 to −6,200 ft) elevation, which is about 400 metres (1,300 ft) below the surrounding plains. It is noted that the crater has undergone various erosion processes, with wind being one cause.

The International Astronomical Union named the crater after a town in Canada, Endeavour, Saskatchewan. The name was approved on 20 October 2008. Due to rules for naming craters, it is officially named after the Canadian town, but the reason this name was proposed was because rover team was using informal nicknames based on a voyage of HMS Endeavour.

An informal working nickname by the Mars mission for the crater was Endeavour, and features of it, are based on the voyage of HM Bark Endeavour, a British Royal Navy research vessel commanded by Lieutenant James Cook on his first voyage of discovery, to Fiji, New Zealand and Australia from 1769 to 1771, using Australian places named by James Cook. Examples include: Cape Dromedary, Point Hicks, Byron Bay, Cape Tribulation, Cape Byron, and Cape York. The purpose of the voyage was to observe the transit of Venus, to accurately measure the distance to the Sun, then to explore lands found on the return journey.

The crater is understood by the 2010s to have two main rock types, the Shoemaker Formation and the Matijevic Formation. It has been classified as a complex crater and it is thought to be so old many of its features have been worn away. Some questions were raised about the tilt of the rim, however understanding is hampered by a lack of knowledge about Martian impact craters: Endeavour was the largest Martian impact crater up to that time to be studied that closely. An example of the difficulty of studying Mars features is also apparent with Orcus Patera, which has various volcanic, tectonic, or cratering events explanations for its formation. One famous Mars realization was that what was then called Nix Olympica was a volcano, and then renamed Olympus Mons thanks to Mariner 9 orbiter observations in the early 1970s. Endeavour was identified as having clay minerals, as detected from orbit by Mars Reconnaissance Orbiter, which according to theories at that time indicated rock from an older, wetter, time period on Mars. This type of rock is different from what prevails in other areas of surrounding plains.

What is expected to be a fluid-carved gully was identified at Endeavour, probably water. This gully is targeted for exploration by the MER-B rover mission as of October 2016. It reached the gully in 2017 and it was named Perseverance Valley