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.
If you mean the last Companion to die, it was Abu At-Tufayl ‘Aamir ibn Waathilah as Imaam Muslim and other scholars asserted. ‘Aamir died in 110 A.H. and some scholars said that he died before that date, as mentioned in Fat-h Al-Baari by Al-Haafith ibn Hajar .
Allaah Knows best.