Stone Men of Saturn

The Kornans in their debut issue

Kronans (a.k.a. the Stone Men of Saturn) were the first villains Marvel Comics' Thor fought.
History
The Kronans live in a military dictatorship. They attempt to conquer new worlds and expand their empire. However, they have little success in doing so. They attempted to conqueror 3000 BCE Earth, but was stopped by Gilgamesh and a time-displaced Captain America. They moved to Saturn hence why they are called "Stone Men of Saturn". They attempted to invade Earth again, but was stopped by Donald Blake / Thor (who had just discovered Mjolnir). They fled since they didn't know if all humans were as powerful as Thor or not. After crashing on an asteroid, they entered suspended animation. When they awoke, they attempted to steal the Star-Jammer (a spaceship piloted by Thor), but lost and the asteroid was destroyed. Another Kronan crew was stranded. After repairing their ship (with help of the Kree), the Stone Men were caught in a space warp and were separated. Kronans were among the aliens attempting to get rights for Rick Jones' biography (in the hope of learning about how he used the Destiny Force), but found the book useless. We met a Kronan Starblasters member named "Zardok". Some Kronans helped the New Immortals led a fight against the High Evolutionary. However, Thor and Godpack defeated them. On Sakaar, the Red King used "obedience disks" (which cause pain) to make the Kronans his slaves. He forced them into gladiatorial combat. The Hulk and the Warbound freed them.
Physical Traits
The Stone Men are silicon-based aliens. They are extremely resistant to heat and cold. The Kronans eat rocks and lack other biological needs (such as sunlight, oxygen and water). In Earth-like environments, they can live for centuries and lift roughly 100 tons. Stone Men can enter suspended animation during which they have limited senses about their environment. They can only be killed if shattered or grounded into dust.
References:
http://marvel.com/universe/Kronans