Though the actual names of these characters haven’t come out, their descriptions do point in a few specific directions.
According to a report from The Illuminerdi, casting is currently underway for Secret Invasion. Three significant roles have come to light in the process, a 50-60 year old male for the main villain of the show, a 40-50 year old woman who will appear alongside Jackson, and a young female supporting character. The specific characters they will be playing have not yet been revealed.
The comic storyline featured Queen Veranke as the main villain of the story, so the fact that a male actor will be starring as the primary antagonist seems to indicate a shift from the source material. The comics themselves have featured a few significant Skrull leaders, perhaps most prominently Emperor Dorrek, whose line held power in the Skrull world for generations. Regardless of which specific character we’ll see on screen, it will likely be some sort of Emperor figure.