Now I will list some of the more "famous" and well-known ones. The first two I want to cover are Ymir and Thyrm. After that I will give more examples and short descriptions of other notable frost etins.
YMIR
As you can imagine, Ymir is a very notable frost-etin. This is because he was the very first, and from him come all other etin (except for the fire-etin). If you understand the norse creation story, it tells us that as Muspellheim and Niflheim drew closer to each other, the heat and cold clashed and melted away the body of Ymir. He was beyond gigantic. (Consider that later on his body parts are used to make whole realms- so his size is beyond massive, beyond the size of one planet). When he was uncovered, he was very primal and primitive (though I say the word primitive with respect to him). By this, I mean that he did not move much, did not think much or want for much. He just was. In truth, if the mysterious cow (Audumhla) did not shoot rivers of milk and feed him, he might have simply faded away, as he made no moves to take care of himself on his own.
Now, as the temperature began to rise he began to sweat more and start moving around- as his body was being uncovered from the ice. The friction provoked from his jerking body ended up creating a man and woman (from his armpit region) and another man from his legs. These were the first technical frost-thurses, and they were unlike the ones we are familiar with today. They were massive in form, completely huge, and had multiple heads. From the mating between these three giants comes the entire race of the frost-thurses. They were different from Ymir in several ways. They moved on their own, thought, etc. As the world of Niflheim came periodically closer to the world of Muspellheim in a sort of dance, a bridge would be made of water which thawed and then froze again. Frost-thurses began to cross the bridge and meet with the sons of Surt, and some of them wedded each other and had children. In this way, the race of giants began to increase). Raven K.
As everyone knows from the story, when this is happening, the cow, Audumhla, is busy licking away the ice and revealing Buri. He was the first Aesir, and the only truly pure-blooded one. I say this, because when he came out of the ice he married a frost-thurse, Bestla. They bore sons, and thus came along Odin, Vili and Ve. To sum up things, the three children end up killing Ymir and using his body to create the realms. However, in doing this they murdered kin, and his blood drowned a great number of the jotunfolk. As you can imagine, this causes a lot of high tension between them- even to this day.
THYRM
Thyrm is the Chief and King of Jotunfolk. However, if you want to get technical, his role is a bit ceremonial- as Utgard Loki is also respected just as much as him, and actually has more power to fulfill the role of a chief. If you think of this in political terms, hes not unlike the Queen of England in his role. His main duty is to bring the jotunfolk together and to help make decisions, peace treaties, and so on. His peaceful nature is apparent in his personality. He is often seen as jovial, happy, and incredibly calm. He loves generosity, and likes to give people gifts, as well as invite people to parties and gatherings. Socializing is one of his strong-points. He loves jokes and to be entertained, whether that be through song, dance, whatever. However, as I mentioned about Jotun nature- under the surface he is not all laughs and games. He is very serious, very dedicated to his causes. If you harass him or anger him, you will face his wrath.
I mentioned that politics can become a problem with the Jotun, and this is the perfect example of that. Thyrm has a distinctive and passionate hate for the Aesir, and you would do best to never mention them in his presence, or again youll face his wrath. He was involved in the stealing of Thors hammer. He was in love with the Vanir goddess, Freyja, and wanted to marry her so he went about it this way- and it did not end pleasantly. If youve heard the story, you know that Thor and Loki dressed up as ladies and Thor pretended to be Freyja. Once he got the hammer back, he killed nearly everyone at the event- though Thyrm escaped with physical and emotion bruising. Even if you are the most dedicated person ever, and you absolutely love the Aesir, leave all talk of them behind you when visiting him. He will appreciate you for it.