The M50 "Ontos" ('Thing' in Greek) was a self-propelled anti-tank vehicle developed in 1951 and fielded by the US Marines from 1956 to 1969, seeing combat in the Vietnam War to great effect. The vehicle was equipped with six 105 mm M40 recoilless rifles (designated as 106 mm to avoid confusion in ammunition supply with the 105 mm M27 recoilless rifles it replaced, despite being the same calibre), as well as a single 7.62 mm machine gun for self-defence and four 12.7 mm machine guns mounted above the M40s to assist in rangefinding. Originally developed for the US Army, the Army cancelled the project in 1955 after working prototypes were built and tested, but as the Marines were quite desperate for AT vehicles, the Ontos made it into production with 297 units produced in total. The vehicle had its fair share of shortcomings, such as a very tall profile for a vehicle of its size, the inability to reload its guns from inside the crew compartment, a limited load of shells carried by the vehicle and a very powerful backblast when firing all six guns at once (at Aberdeen, the vehicle managed to shatter windows and knock bricks off buildings during testing!), but despite this, during the Vietnam War it saw quite effective use by the Marines. The vehicle's ability to fire all six guns at once at a position meant that all but the strongest fortified structures fell apart when struck quite easily, and as the guns were recoilless rifles, a quick getaway after firing was also possible, leading to low loss rates. Its light weight (9 tons) and much less constrained urban combat abilities meant it saw great success during the war, although the vehicles were almost all used up during the conflict and were mostly sold off for scrap or repurposed as construction vehicles after 1969, with 14 still remaining in various museums.

Introduced in Update 1.71 "New E.R.A.", the M50 "Ontos" is quite a peculiar vehicle, with its nickname describing it very well; and what a thing it is indeed! Equipped with six M40 106 mm recoilless rifles on a turret that can rotate 40 degrees in either direction, the Ontos offers a compact, lethal package of HEAT or HESH warheads that can be fired in quick succession at an unsuspecting target. The M50's game plan revolves around not being seen, flanking/ambushing enemies and then punishing them with overwhelming firepower, all things the vehicle excels at due to its high mobility and good gun angles (most notably its -10 degrees of gun depression). However, the vehicle lacks any semblance of armour, and aside from autocannon HE shells or low-penetrating guns of much lower BRs, your armour will not stop any enemy fire, making the Ontos very much a glass cannon in line with the M56 that comes before it. Your ability to fire multiple shots before reloading can also enable firing on the move if you're particularly bold or in a rush, as one miss is not as impactful as on other vehicles, although it is still more desirable to ambush your enemies rather than rushing them down. All-in-all, the M50 is a highly versatile vehicle with above-average mobility, excellent firepower (albeit with a slightly long reload once you expend all six shells in a clip) and very thin armour, and excels when played like a light tank or when facing vehicles of a higher BR that have very thick armour from the front.