Important! The list seen below doesn't feature unique enemies or creatures that appear only once during the game and that often are considered to be bosses. It also doesn't feature wild animals which aren't hostile towards the main character (deers, foxes, rabbits etc). Remember that the experience level of the creatures you encounter often raises when the main character advances to higher levels. Don't expect that exploring the same location while being on the 5th and 30th experience level will feature much easier fights the second time around, because it's likely that your enemies will pose a similar threat.
These powerful magical beings are often summoned by enemy mages and they appear in three different forms - as fire atronachs, as frost atronachs and as shock atronachs. Remember that atronachs are partially immune to the elemental powers they represent (for example, fire atronachs are partially immune to fire damage). The easiest way to get rid of the atronachs is to kill the mages who summoned them to the battlefield.
Common bandits may represent all character classes, however you'll be dealing with warriors and archers for most of the game. Bandit mages are a rare thing, but if they do appear they pose a serious threat. Some bandit groups have leaders and you'll have to watch out for them, because they're usually harder to kill.
Bears are formidable opponents and you shouldn't start fights with them unprepared, because they can inflict some serious damage. Make sure to avoid their power melee attacks and move around a lot, especially since they're slower than wolves and sabretooth cats. You can encounter polar bears in the mountain areas of Skyrim and it's good to remember that they're partially immune to frost damage.
The chaurus occupy the same locations as falmers, so you may encounter them mostly in ruins, dungeons and caves. It's important to always focus on a single creature, because they're resistant and they can't be killed quickly. You should also check your health after each battle, because the chaurus can poison their victims.
You'll encounter a lot of dragons while completing the main quests, however you will also be bothered by them on a regular basis while travelling the world. It's worth mentioning that fire-breathing dragons have reduced resistance to frost damage and frost-breathing dragons have reduced resistance to fire damage. Be very careful while going against blood dragons, because they're stronger than other types of these creatures.
Draugrs are a very common type of an enemy, because these undead creatures can be found in almost every crypt and dungeon that you explore during the game. Draugrs appear in many different types. It's easy to deal with their basic forms, however elite draugrs may prove to be a serious challenge. I recommend that you're extremely careful while fighting scourges, overlords and deathlords, especially if the undead you've encountered are capable of casting spells. It's worth mentioning that all draugrs are partially immune to frost damage and completely immune to poisons.
You won't encounter a lot of dremora in the game, however you must be careful each time you're fighting them, especially if the dremora you're trying to defeat can cast powerful spells. Try to avoid their attacks if possible and always focus on killing one dremora before moving on to the next one.
The centurions can only be encountered in dwarven ruins and they always pose a very serious threat. I strongly recommend that you keep them at a safe distance, because they may quickly kill you if they manage to get closer. You should use the fact that centurions are very big and therefore can't use smaller passageways and entrances. All the centurions are fully immune to frost damage and partially immune to magic.
The spheres can only be encountered in dwarven ruins (with a few exceptions) and their specialization is inflicting a lot of damage in melee combat. As a result it's crucial that you maintain safe distance from them, because they can't attack you from far away. All the spheres are fully immune to frost damage and partially immune to magic.
The spiders can only be encountered in dwarven ruins (with a few exceptions) and their primary attack is usually an attempt to inflict shock damage. Attack one spider at a time, because they are resistant to damage and can't be destroyed right away. All the spiders are fully immune to frost damage and partially immune to magic.
Falmers live only underground and you can usually encounter them while exploring dungeons and dwarven ruins. Be careful, because most of them can inflict serious injuries and they're also quite strong. Always focus on eliminating falmer mages in order to prevent them from casting very powerful spells.
Forsworn occupy a lot of locations in the game and you'll be encountering them mostly while completing main quests. Weaker types of the forsworn aren't hard to kill and aren't a serious threat, however the same can't be said about their shamans and they're the ones that should always die as soon as possible.
GHOSTS / SPIRITS
The ghosts usually act the same way as their living versions and depending on what type of a ghost you've encountered they may be very easy to kill or they may pose a challenge. It's important to remember that you don't have to rely on magic while fighting the ghosts, because melee and ranged weapons can also harm them.
Giants are among the most powerful creatures you can encounter during your journeys. Sadly it's much harder to keep them in a safe distance than mammoths, because they're quite fast for their size. As a result you should always focus on slowing them down or at least try blocking their club attacks. It's worth mentioning that most giants will leave you alone unless they're provoked (not only by attacking them, but also by entering their territory).
Horkers are reasonably large creatures, however killing them usually isn't a big problem. You can encounter them mostly in the northern part of Skyrim and during the fights you should use the fact that they're very slow.
Despite what you might think you don't have to use any magic while fighting the ice wraiths, because a melee weapon or a range weapon can also injure them. An important thing to remember is that all wraiths are fully immune to frost damage. They have reduced resistance to fire damage on the other hand and it's wise to use that to your advantage.
Expect to be forced to eliminate a lot of the soldiers of the Imperial Legion if you've joined the civil war and taken side of the Stormcloaks rebellion. Notice that a lot of Imperials are heavily armed and well equipped. Avoid larger groups if possible, because you may die easily if you get surrounded.
MAGES - CONJURERS
Conjurers can be members of different races and they can act alone or they can appear with other types of enemies. It's recommended that you focus your attention on killing them quickly, because all the magical creatures they've summoned will die along with them.
MAGES - NECROMANCERS
Necromancers can be members of different races and they can act alone or they can appear with other types of enemies. It's recommended that you focus your attention on killing them quickly, because all the dead they've resurrected will die along with them.
Mammoths are among the most powerful creatures you can encounter during your journeys and it's always a good idea to attack them from a distance or at least to focus on defending from their melee attacks (you should also use the fact that they're rather slow). It's worth mentioning that most mammoths will leave you alone unless they're provoked (or if you'll attack giants that accompany them).
Crabs are among the weaker creatures living in Skyrim, however they may be successful at surprising you, because they often like to hide near the water.
Mages that specialize in casting offensive spells can be members of different races and they can act alone or they can appear with other types of enemies. Make sure to take some time to analyze each group so that you'll have a chance to defend better against the types of spells they like to cast (for example - spells which inflict fire damage).
This is a very unique category of enemies, because the undead can be anyone that's been brought back to life thanks to necromancer's spells. Make sure to focus on attacking the necromancer responsible for this deed, because it's the most efficient way of getting rid of all the undead in the area.
Sabretooth cats usually pose a serious threat and this means you must be careful while fighting them to ensure that the main character won't suddenly die. Snow sabre cats can be encountered in the mountain areas of Skyrim. They're not stronger than the usual sabre cats, but they're partially immune to frost damage.
Skeevers are like big rats and they're not a serious problem, so even if your character is very weak you can still easily get rid of them.
Skeletons can usually be found in the same locations where you're fighting draugrs, so expect to encounter them while exploring crypts, dungeons and ruins. Eliminating these undead creatures shouldn't be a big problem, however you should know that skeletons can be warriors and archers.
Smaller spiders are very easy to kill, however the same thing can't be said about their larger versions. They usually inflict serious injuries and have a lot more health. Make sure to check your health after each battle, because the spiders can poison their victims.
Spriggans are a rare group of enemies and they can be encountered mostly while exploring various groves. Use fire attacks if possible when going against these creatures, because that's their primary weakness. Don't forget to be careful when fighting much stronger spriggan matrons (they act as leaders of the groups of spriggans).
Expect to be forced to eliminate a lot of the members of the Stormcloaks rebellion if you've joined the civil war and taken side of the Imperial Legion. Notice that some of the Stormcloaks are heavily armed and well equipped. Avoid larger groups if possible, because you may die easily if you get surrounded.
The thalmor aren't a frequent type of an enemy. You'll encounter them while exploring their embassy as a part of one of the main quests and on several other occassions. They're usually very skilled warriors and archers, however you may also encounter thalmor mages and obviously they pose a serious threat so you must be careful.
Trolls are formidable opponents and you shouldn't start fights with them unprepared, because they can inflict some serious damage. Don't forget that trolls can only injure you in close combat and they're helpless if you attack them from a distance. You should also know that trolls have an ability to regenerate their health, so they should never be left alone for too long. The good news on the other hand is that trolls have a reduced resistance to fire attacks.
Most vampires you encounter are aggressive and they usually hide out in caves. Only a small number of vampires can be found above ground and typically they're friendly when you first meet them. Make sure to always focus on one target when you're fighting the vampires and also try blocking their spells if you can. It's worth mentioning that vampires are partially immune to frost attacks and they also have reduced resistance to fire attacks. Make sure to check your health after each battle, because you can be infected with vampirism (more on that in the previous chapter of the guide).
Wisps aren't a serious threat on their own and you don't have to use only spells to destroy them, because you may as well rely on melee or ranged weapons. You must watch out on the other hand for wispmothers which sometimes accompany the wisps. They're much harder to kill, especially since wispmothers can heal themselves and summon magical shades to assist them.
"Normal" witches are a rare thing and it's very easy to defeat them. It's the hagravens you should be worried about and you must treat them as powerful mages. This means you should attack them in close combat or at least block or dodge their magical attacks (they like to cast fireballs among other offensive spells).
Wolves are among less powerful creatures encountered during your journeys, however you must remember that they always attack in packs. This means you should eliminate them in a certain order instead of attacking all the wolves at once. You can encounter snow wolves in the mountain areas of Skyrim and it's good to remember that they're partially immune to frost damage.