Did Prophet Muhammad (peace and blessings be upon him) Kill Anyone?
Question

Did Prophet Muhammad (peace and blessings of Allah be upon him) kill any enemy during the battles he took part in?
Praise be to Allah.Al-Bukhari (4073) and Muslim (1793) narrated that Abu Hurayrah (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings of Allah be upon him) said: “The anger of Allah is most intense against a man who is killed by the Messenger of Allah for the sake of Allah (on the battlefield).” 
Al-Nawawi said: 
“For the sake of Allah” excludes one whom he kills as a hadd punishment or by way of legal retaliation (qisas), because whoever is killed by the Prophet (peace and blessings of Allah be upon him) on the battlefield was intending to kill the Prophet (peace and blessings of Allah be upon him). 
It is not known that the Prophet (peace and blessings of Allah be upon him) killed anyone among the mushrikeen with his own hand apart from Ubayy ibn Khalaf. 
That was narrated by Ibn Jarir and al-Hakim from Sa’id ibn al-Musayyab and al-Zuhri (may Allah have mercy on them). Ibn Kathir said in his Tafsir (2/296): its isnad is sahih. 
Ibn al-Qayyim said – when discussing the battle of Uhud –  
“The Prophet (peace and blessings of Allah be upon him) turned towards the Muslims, and the first one who recognized him beneath his armour was Ka’b ibn Malik, who shouted at the top of his voice, “O Muslims! Rejoice! This is the Messenger of Allah (peace and blessings of Allah be upon him)!” He gestured to him to be quiet, and the Muslims gathered around him and went with him to the mountain pass where he had camped. Among them were Abu Bakr, ‘Umar, ‘Ali, al-Harith ibn al-Simmah al-Ansari and others. When they got close to the mountain, Ubayy ibn Khalaf, who was on a horse of his whose name was al-‘Iwadh, caught up with the Messenger of Allah (peace and blessings of Allah be upon him). 
The enemy of Allah had claimed that he would kill the Messenger of Allah (peace and blessings of Allah be upon him) whilst riding this horse. When he got close to him, the Messenger of Allah (peace and blessings of Allah be upon him) took a spear from al-Harith ibn al-Simmah and killed him with it. It hit him in his collarbone and the enemy of Allah retreated in defeat. The mushrikin said to him, By Allah, there is nothing wrong with you. He said, By Allah, if what is wrong with me had happened to the family of Dhu’l-Majaz, they would all have died. He used to feed his horse in Makkah and say, I will kill Muhammad riding it.
News of that reached the Messenger of Allah (peace and blessings of Allah be upon him) and he said: “Rather I will kill him, in sha Allah.” When he stabbed him, the enemy of Allah remembered that the Prophet (peace and blessings of Allah be upon him) had said, “Rather I will kill him,” and he was certain that he would die from this wound. And he died from it in Sarif on his way back to Makkah.” (Zad al-Ma’ad, 3/199)
For more, please see this category: Biography of the Prophet 
And Allah knows best.