Colonel Marie Augstin Gaston Cros (known as Gaston Cros) (6 October 1861 – 10 May 1915) was a French army officer and archaeologist. He was born in Alsace and was displaced when that territory was incorporated into the German Empire. He joined the French Army as a lieutenant and saw action in Tonkin before spending several years surveying in Tunisia, receiving the honours of membership of Vietnamese and Tunisian orders and appointment as a chevalier of the Legion of Honour. In 1901 Cros was appointed head of the French archaeological expedition to Girsu, Iraq to continue the work of Ernest de Sarzec. His work over the next five years included the tracing of the 32.5-foot-thick (9.9 m) city wall, and for his work there he received a letter of commendation from Gaston Doumergue, the Minister of Fine Arts, and the award of the Golden Palms of the Ordre des Palmes Académiques. Promoted to lieutenant-colonel, Cros served in the French protectorate of Morocco from 1913, seeing action in the Zaian War.

Upon the outbreak of the First World War Cros was recalled to metropolitan France and fought in defence of Paris at the First Battle of the Marne, leading an ad hoc unit of zouaves and tirailleurs. He was wounded and spent two days directing his troops from a horse-drawn carriage before he was forced to leave his command. On 15 September 1914 he was promoted to colonel and subsequently received command of the 2nd Moroccan Brigade, which he led at the Battle of the Yser and the Second Battle of Artois. It was at Artois that he was killed in a German counter-attack. Cros' name is recorded alongside that of Colonel Pein, who commanded the 1st Moroccan Brigade at Artois, on the Moroccan Division Memorial at Vimy.

Marie Augstin Gaston Cros was born at 2.00am on 6 October 1861 to Hippolyte Cros, a lawyer, and Marie Petronille Reine Scherb at Saverne, Bas-Rhin in the Alsace region. After Alsace was incorporated into the German Empire after the Franco-Prussian War of 1871 Cros' family chose to retain their French nationality and moved to Lunéville in Meurthe-et-Moselle. Cros volunteered for a five-year commission with the French Army on 25 October 1881 at Nancy. Four days later he was enrolled into the Ecole Spéciale Militaire de Saint-Cyr as a cadet, from which he graduated on 1 October 1883, ranked 261 out of 342 in his class. Cros was commissioned into the 128th Infantry Regiment as a sub-lieutenant and attended the L'Ecole du Tir (marksmanship school) in 1885 where he ranked 25th out of 76 participants.

Cros transferred to the 4th Tonkinese Rifles on 3 June 1887 and saw active service in Tonkin (northern Vietnam) from 19 June 1887 to 14 September 1888, joining the 105th Infantry Regiment as a lieutenant on 5 October 1887. He was awarded the Tonkin Expedition commemorative medal for his work in the country.

On 25 January 1889 Cros transferred to the 4th Zouave Regiment and was on active service in Tunisia from 11 March 1889 to 27 April 1898. He was attached to the Army Geographic Service from 1891 to 1893, and made several topographical surveys of the Sahara desert. Cros was appointed a knight of the Order of the Dragon of Annam and a member of the Tunisian Order of Glory on 10 October 1889 in recognition of his service in Tonkin and Tunisia. He was promoted to captain on 10 July 1894 and became a chevalier of the Legion of Honour on 29 December 1896. Cros transferred to the 39th Infantry Regiment on 5 April 1898 and served with them in Algeria from 11 November 1899 to 1 June 1900.

From December 1901 Cros was placed in charge of the French-led Tello Expedition to the archaeological site of Girsu in Iraq. He replaced the late Ernest de Sarzec, the French consul of Basra, who died in 1901 and had been excavating Tello since 1877, having initiated the rediscovery of the Sumerian civilization. The appointment of a military man to this position might have been influenced by the revolt of the Muntafiq Arabs against the Ottoman Empire which created a hostile environment for the archaeologists. Cros' knowledge of archaeology, like Sarzac's, came from a purely amateur interest in the subject though he had a thorough understanding of desert topography from his surveying days. One of Cros' first acts was to move the site of the French camp nearer to the excavation area, having been previously situated an hours ride away. This made it less defensible and further from the water supply but he solved these problems by negotiating protection from the local Karagul Arabs and co-ordinating the construction of a new reservoir supplied with water by caravan convoys.

Cros undertook numerous excavations at Tello producing significant numbers of artefacts, some dating from the earliest periods of Sumerian civilization. One of his achievements, considered his most important at Tello, was the tracing of the great city wall which was 32.5 feet (9.9 m) thick. In 1903 he discovered a doorway in the vicinity of de Sarzac's famous cuneiform tablets that provided evidence that the tablets were stored as part of a state administrative archive.

During his time at Tello he remained nominally with the 39th Infantry Regiment, transferring to the 80th Infantry Regiment on 17 February 1903. His archaeological work was recognised by promotion to chef de bataillon (roughly equivalent to major), in the 116th Infantry Regiment, on 24 June 1905 and by appointment as an officer of the Legion of Honour on 12 March 1906.