Venomm
Having spent most of his time studying and learning how to manipulate his reptile buddies, Venomm began using them as a weapon, building natural immunity to their venomous bites.
Baron Zemo
It's his organizational and leadership skills that make him such a formidable threat, including his stints putting together the Masters of Evil — one of the foremost groups to oppose the Avengers.
Ulysses Klaw
Losing his right hand to T'Chaka's son and successor, T'Challa, Klaw became one of Black Panther's most persistent antagonists, as well as battling the Fantastic Four, the Avengers, and Ka-Zar.
Namor
Over the decades, he's blurred the lines between traditional hero and villain, aligning himself with the Avengers, the Fantastic Four, and the X-Men, while also occasionally combating those same groups.
Doctor Doom
While he's traditionally considered the arch-enemy of the Fantastic Four, the good doctor has also been portrayed as an occasional enemy of Black Panther.
Erik Killmonger
Seeking to avenge his parents' deaths, Killmonger became a top-ranked mercenary working for the likes of Kingpin, before journeying back to Wakanda as a revolutionary leader.