I googled “grandes historiadores portugueses”.
The best result I got was from:
From there I found something interesting:
Historians from the Island of Madeira:
From there I found: Joel Serrão. Maybe the best known to the general public.
He died in 2008 in Santana (Sesimbra).
Besides the wiki article, you can see a photo of him and read some more about him as well, here: