Panther
during the invasion of soviet union , German panzer tropps encountered the Soviet T34/76 and KV series which were far superior to any German tank in terms of firepower and armor protection and maneuverability. Due to constant needs on the eastern front in November 1942 , Adolf hitler ordered the production of a new 30 ton medium tank . Damiler Benz and MAn recieved the order for production in December.  the new 30 ton vehicle was to be armed with 75mm KwK L/70 gun. Hitler insisted on using 75mm KwK L/100 gun, but since it was not ready at that time the L/70 gun was chosen for the new tank. Panther's 75mm gun had slighty more penetration than Tiger's 88mm gun.Rheinmetal Borsig was in charge of producing the turret and gun.  Benz had already prepared a design in the summer of 1941 . The benz's design was a directo copy of the soviet T 34/76, the project was rejected. Benz prepared its second design based on the previous design. The new design was very similar to T34/76. MAN's design was prepared in spring 1942. Prototypes were made and were shown to Adolf Hitler . On 11th May 1942 the project recieved the name Panther and 3 days later after extensive tests MAN's design was chosen  for full scale production. Benz's design was rejected because it might have caused confusion in the battle field for the German troops in Identifing firend from Foe and it was also less reliable. Hitler ordered MAN to start production of Panther in December 1942.
Ausf D was produced in december of 1942. Hitler ordered 250 units to be prepared for operation Zitadelle and 750 to be ready as soon as possible. Many of the Panthers prepared broke down because of electrical problems and also problems with gearbox.  After the operation out of 250 Panthers ordered only 47 were operational and they were later converted to Command Vehicles.  Next series of 700 Ausf Ds produced were powered by 700hp engine which became the standard engine for other variants.
In March 1944 Ausf G was produced. 2950 units were manufactured
Ausf G was the most powerrful Panther produced and its chassis was used to produce the Jagdpanther. It had a more powerful 75mm gun and additional armor protection.
Total 6000 Panthers were manufactured by MAN,MNH, Daimler Benz, and Henschel.
In February 1943 Fiat aquired licence to produce Panther but the production never took place because of Italian surrender in September 1943.
In May 1944 Ausf F design was prepared with increased armor a newly designed narrow turret. It was planned to start production of the new Ausf F in March 1945. Benz managed to produce a single Ausf F in January 1945 because of overall war situation.
Panther's chassis was used for many conversions like many other German tanks. Perhaps the best conversion ever made was the Jagdpanther. Panther II was also designed. It was a more powerful version of Panther with increased armor protection and firepower . Panther II never went beyond the prototype stage.
Panther was probebly the best German tank during the WW2. Its 75mm long barreled gun could destroy any enemy tank from range of 2000m.  Its long barreled gun , Wide tracks , slopping armor ( first German tank to have sloping armor ) high maneuverability because of its light weight made Panther a formidable weapon. although Panther was the best German tank , it suffered from lack of testing , it was rushed into production and many of its problems were not solved until the end of the war. Perhaps this was the reason that Guderiannamed Panther as : Our  Problematic Child "