There's no direct tie between Thanos and the Skrulls, but both are the result of genetic experimentation by the Celestials. The Skrulls were also originally separated into Eternal and Deviant classes, though in their case the Deviants became the dominant race.

Is Thanos Kree or Skrull?

Thanos, although born to Eternal parents, is altered due to a genetic disorder, making him a Deviant. The Skrulls, on the other hand, are all Deviants. A billion years ago, the Celestials visit Skrullos. From the primitive race, they forged three variants: Prime Skrulls, Eternal Skrulls, and Deviant Skrulls.

What race is Thanos?

Powers and abilities

Thanos is a mutant member of the race of superhumans known as the Titanian Eternals.