Khosrau II or Khosrow II (Chosroes II in classical sources, sometimes called Parvez, "the ever Victorious" – in Persian: خسرو پرویز) was the twenty-second Sassanid King of Persia from 590 to 628. He was the son of Hormizd IV (579–590) and grandson of Khosrau I (531–579).

Biography
Khosrau II was much inferior to his grandfather. He was haughty and cruel, rapacious and given to luxury; he was neither a general nor an administrator. He had a harem of over 10,000 concubines, and when Arab Na'aman refused Khosrau his daughter, he had him crushed by elephants.

Personality and skills
Khosrau II was raised to the throne by the magnates who had rebelled against Hormizd IV, who soon after had his father blinded and killed. But at the same time the general Bahram Chobin had proclaimed himself King Bahram VI (590–591), and Khosrau II was not able to maintain himself.
The war with the Romans, which had begun in 571, had not yet come to an end. Khosrau II fled to Syria, and persuaded the Emperor Maurice (582–602) to send help. Many leading men and part of the troops acknowledged Khosrau II, and in 591 he was brought back to Ctesiphon. Bahram VI was defeated and he fled to the Turks of Central Asia, among whom he was murdered. Peace with Rome was then concluded. Maurice made no use of his advantage; he merely restored the former frontier and abolished the subsidies which had formerly been paid to the Persians.

Accession to the Throne
At the beginning of his reign, Khosrau II favoured the Christians; but when in 602 Maurice had been murdered by Phocas (602–610), he began war with Rome to avenge his death. His armies plundered Syria and Asia Minor, and in 608 advanced to Chalcedon.
In 613 and 614 Damascus and Jerusalem were taken by the general Shahrbaraz, and the True Cross was carried away in triumph. Soon after, General Shahin marched through Anatolia and conquered Egypt in 618. The Romans could offer but little resistance, as they were torn by internal dissensions, and pressed by the Avars and Slavs.

Military Exploits and Early Victories
Ultimately, in 622, the Emperor Heraclius (who had succeeded Phocas in 610 and ruled until 641) was able to take the field. In 624 he advanced into northern Media, where he destroyed the great fire-temple of Ganzhak (Gazaca); in 626 he fought in Lazistan (Colchis). In 626, Persian general Shahrbaraz advanced to Chalcedon and tried to capture Constantinople with the help of Persia's Avar allies. His attempt failed, and he withdrew his army from Anatolia later in 628.
Following the Khazar invasion of Transcaucasia in 627, Heraclius defeated the Persian army at the Battle of Nineveh and advanced towards Ctesiphon. Khosrau II fled from his favourite residence, Dastgerd (near Baghdad), without offering resistance; some of the grandees freed his eldest son Kavadh II (he ruled briefly in 628), whom Khosrau II had imprisoned, and proclaimed King (night of 23-4 February, 628). Four days afterwards, Khosrau II was murdered in his palace. Meanwhile, Heraclius returned in triumph to Constantinople; in 629 the Cross was given back to him and Egypt evacuated, while the Persian empire, from the apparent greatness which it had reached ten years ago, sank into hopeless anarchy. It was overtaken by the armies of the first Islamic Caliphs beginning in 634.

Turn of Tides
Khosrau II (Arabic كسري) is also remembered in muslim tradition to be the Persian king to whom the Islamic prophet Muhammad had sent a messenger, Abdullah ibn Hudhafah as-Sahmi together with a letter to preach the religion of Islam. In Tabari's original Arabic manuscript the letter to Khosrau II reads:
بسم الله الرحمن الرحيم من محمد رسول الله الى كسرى عظيم الفارس . سلام على من اتبع الهدى و آمن بالله و رسوله و شهد ان لااله الا الله وحده لاشريك له و ان محمد عبده و رسوله. ادعوك بدعاء الله، فانى رسول الله الى الناس كافة لانذر من كان حيا و يحق القول على الكافرين. فاسلم تسلم . فان ابيت فان اثم المجوس عليك .
English translation:
In the name of Allah, Most Gracious, Ever Merciful From Muhammad, Messenger of Allah, to Chosroes, Ruler of Persia. Peace be on him who follows the guidance, believes in Allah and His Messenger and bears witness that there is no one worthy of worship save Allah, the One, without associate, and that Muhammad is His Servant and Messenger. I invite you to the Call of Allah, as I am the Messenger of Allah to the whole of mankind, so that I may warn every living person and so that the truth may become clear and the judgment of God may overtake the infidels. I call upon you to accept Islam and thus make yourself secure. If you turn away, you will bear the sins of your Zoroastrian subjects.
The Persian historian Tabari continues that in refusal and outrage, Khosrau tore up Mohammed's letter and commanded Badhan (Persian: باذان), his vassal ruler of Yemen, to dispatch two valiant men to identify, seize and bring this man from Hijaz (Muhammad) to him. The narration carries on with trivial accounts of their encounter and dialogue with Muhammad and conversion of Badhan (Bāzān) and the whole Yemenite Persians to Islam subsequent to receipt of shocking tidings of Khosrau's murder by his own son, Kavadh II (Persian: شيرويه Shirouyeh).

In art

Shirin Beloved wife of Khosrau
Non-Muslims Interactants with Muslims During Muhammad's Era