Sayyidina ‘Uthman radiya Llahu ‘anhu was the third Khalifah, Dhu al Nurayn—the one married to two of the daughters of the Prophet salla Llahu ‘alayhi wa sallam, Sayyidah Ruqayyah and Sayyidah Umm Kulthum radiya Llahu ‘anhuma, the martyr of the house.
He is ‘Uthman, the son of ‘Affan, the son of Abi al ‘As, the son of Umayyah, the son of ‘Abdul Shams the son of ‘Abd Manaf, the son of Qusay, the son of Kilab.
His genealogy meets with that of the Prophet salla Llahu ‘alayhi wa sallam at ‘Abd Manaf.
His mother was Arwa, the daughter of Kurayz, the son of Rabi’ah, the son of Hubayb, the son of ‘Abdul Shams, the son of ‘Abd Manaf. Her genealogy meets with the Prophet salla Llahu ‘alayhi wa sallam at ‘Abdul Manaf as well. The mother of Arwa was Umm al Hakim (al Bayda’), the daughter of ‘Abdul Muttalib—aunt of the Prophet salla Llahu ‘alayhi wa sallam—who was the twin sister of the Prophet’s father, ‘Abdullah.
The son of Amir al Mu’minin, ‘Ali ibn Abi Talib, was martyred alongside his brother, Sayyidina Hussain, in Karbala’. His mother is Umm al Banin bint Hizam al Wahidiyyah al Kilabiyyah.
Al Baladhuri said:
Also born was ‘Uthman, Jafar al Akbar, and ‘Abdullah; they were killed alongside Hussain radiya Llahu ‘anhu.
There is a possibility that Sayyidina ‘Ali radiya Llahu ‘anhu may have named two of his sons ‘Uthman, ‘Uthman al Akbar (mentioned above) and ‘Uthman al Asghar, just as he may have named two of his sons ‘Umar, ‘Umar al Atraf and ‘Umar al Asghar.
As mentioned by al Mas’udi in Muruj al Dhahab (2/413) and al Tustari in Tawarikh al Nabi wa al Al (pg. 118).
The nephew of Amir al Mu’minin ‘Ali ibn Abi Talib, the son of his brother ‘Aqil, was also given the name ‘Uthman.
Al Baladhuri said:
Aqil had the sons Muslim…’Uthman.
Ibn Hazm said:
The children of ‘Aqil ibn Abi Talib: ‘Abdullah, ‘Abdul Rahman—who were killed alongside Hussain radiya Llahu ‘anhu, Muslim—who was killed in Kufah, ‘Ali, Hamzah, Jafar, Sa’id, Abu Sa’id, ‘Isa, ‘Uthman, and Yazid—from who he received his agnomen (Abu Yazid).
His genealogy meets with the of ‘Ubaidullah al A’raj ibn Hussain al Asghar ibn ‘Ali ibn Hussain al Shahid
Sayyidina Hussain radiya Llahu ‘anhu, who the Shia consider to be the third infallible Imam also named his son ‘Uthman.
 Despite this noble ancestry and link to the Prophet salla Llahu ‘alayhi wa sallam, ‘Uthman radiya Llahu ‘anhu has not been spared from having his ancestry besmirched. Refer to the likes of al Kalbi in Mathalib al ‘Arab with the research of Najah al Ta’i. From him a number of people who haven’t the slightest knowledge of genealogy have quoted such as in Ilzam al Nasib (with the research of ‘Abdul Rida al Najafi) pg. 165, and al Sirat al Mustaqim ila Mustahiqi al Taqdim 3/30; wherein one can see the manner in which his ancestry has been belittled. If one seeks the ancestry of ‘Uthman radiya Llahu ‘anhu he may refer to al Jawharat Fi Nasab al Nabi salla Llahu ‘alayhi wa sallam wa al Asharah of Tilimsani (2/177), al Isabah pg. 790, # 683, Usd al Ghabah 3/584.
 Ansab al Ashraf pg. 70
 Jamaharat al Ansab al ‘Arab pg. 69