I wish to add some more names and details to complement the respected Sayyid al-Musawi's clear response to this question.
Overall, a good book one can refer to for names of the nawasib - enemies of the Ahl al-bayt (a) - who appear in Sunni hadith is Hashim Ma`ruf al-Hasani's Dirasat fi’l hadith wa’l muhaddithin published in Beirut.
Here are some more examples of such ignoble people appearing in Sunni hadith sources.
1. `Umar b. Sa`d
This narration is not authentic at all, not only among our Shia Ulama but even among many Sunni Ulama like Maalik Bin Anas and other leading Sunni Ulama , who denied the existence any such Hadeeth.
Wassalam
There ae different opinions among the scholars in this matter.
Al Haafidh Abu Na'eem sated in Hilyat Al-Awliyaa that Ima Al-Ridha had six sons and Jafar is one of them.
Mohammad Ibn Talha al-Shafi'ee had the same opinion.
Many of our scholars including Shaikh Al-Mufeed and Al-Erbily narrated from Imam Radha (AS) that he wl have only one son (Imam Al-Jawad) and Allah (SWT) will grant this one son lot of sons.
Wassalam
The books of Bukhari and Muslim narrated from many persons who were open enemies of Imam Ali (AS) like Imran Ibn Hattaan عمران بن حطان who was a Kharijite who praised Ibn Muljim the murderer of Imam Ali (AS). Huraiz Ibn Uthman Al-Himsi is also one of the narrators in Bukhari. He was also a well known enemy who was cursing Imam Ali (AS) from the pulpit. Tahtheb Al-Tahtheeb By Ibn Hajar Al-Asqalani 1:159.
There are many of such narrators you can find them in the books of Ilm Al-Rijaal.
Imam Al-Mahdi (AS) is the twelfth and last Imam in Islam. The Prophet Muhammad (SAWA) has clearly said that (My successors will be twelve, all of them will be from Quraysh) Saheeh Al-Bukhari; Hadeeth number 6682 and Saheeh Muslim; Hadeeth number 3393 and 3394 and 3395 and 3396 and 3397.
Imam Al-Mahdi (AS) was born in Samarra in Iraq on 15 Sha'ban 255 After Hijra when the tyrant government of Abbasid were after trying to kill him knowing from hundreds of Hadeeths that he will be the Imam who will establish the Justice on this earth and remove all the tyrants.