If you don’t want to know who Jude Law is playing in Captain Marvel, don’t look at his action figure for the film.
Before Caron Danvers inherited the mantle of Captain Marvel, that title (at least in Marvel Comics) belonged to a member of the Kree alien race named Mar-Vell.
Yon-Rogg thinks if he can kill Captain Mar-Vell in a way looks accidental, he can then claim Una for himself.
The persistent rumor for months and months was that Law was playing Mar-Vell in Captain Marvel as a kind of mentor figure to Brie Larson’s Danvers.