Malvegil son of Celebrindor is most notable for the fact that, during his reign over Arthedain, the Witch-king founded the realm of Angmar to the east. In Malvegil's lifetime there is no record of any open warfare between the two nations, but a devastating war lay in the future. Some seven centuries of conflict were to come, and eventually Angmar and its allies would leave the kingdom of Arthedain in ruins.
Nonetheless, the emergence of Angmar saw evil things multiply in the eastern lands, driving a westward migration across Eriador. Notable among those travelling out of the east were the Hobbits, and it was during Malvegil's time as King that the main Hobbit settlement in Bree took place.
It is recorded that during Malvegil's reign the line of Isildur had died out entirely in both Cardolan and Rhudaur, and thus the King attempted to reclaim those lands and reunite the old realm of Arnor. Both the lesser realms resisted this, but from the time of Malvegil's son Argeleb I, it became traditional for each King of Arthedain to take their name with a prefix 'Ar-' or 'Ara-', meaning 'royal', to denote their status as Heirs of Isildur.
Malvegil ruled Arthedain for seventy-seven years, and was succeeded by his son, Argeleb I.
Notes
1
The date of Malvegil's birth appears only in The History of Middle-earth volume XII, The Peoples of Middle-earth. It cannot therefore be considered completely reliable.
2
Malvegil's name seems to contain the elements mal 'gold' and gil 'star', though some sources suggest the influence of megil, an old Elvish word for 'sword', and possibly also weg 'man'.