Which Companion accepted Islam at the hands of a Taabi'i (member of the generation after the Companions)?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.

Your question seems to be one of competitions and quizzes. We usually do not answer these questions because we have many important questions whose askers are waiting for an answer.

However, we say that the Companion whom you referred to is ‘Amr ibn Al-‘Aas who embraced Islam at the hands of An-Najaashi, who is considered to be among the Taabi’is [because he did not meet the Prophet, albeit he lived at the same era as his].

Mubaarak Poori said in Tuhfatul-Ahwadhi about an-Najaashi, “‘Amr ibn Al-‘Aas embraced Islam at his hands before he [Amr ibn Al-‘Aas] became a companion of the Prophet . So people ask a puzzling question about him, saying: A companion who narrated many ahaadeeth and who became a Muslim at the hands of a Taabi’i.”

Allaah knows best.