Followers

Followers are companions who can be recruited to travel with you, battle for you, and carry items for you. They can also be given pieces of equipment (weapons and/or apparel), and will equip the weapon with the highest damage value and the pieces of apparel with the highest armor value, as long as those values are higher than their starting equipment.

Followers will retain their inventories after you dismiss them. In this way, it is possible to use them for limited storage, as long as you do not lose access to them somehow (e.g. by turning them against you, or by having them killed).

You can only have one follower with you at a time, but in most cases there is no penalty for dismissing a follower and then re-recruiting them later.

Companions stagger and kneel when their health reaches zero, they automaticlly revive after a short time. Companions can only be killed by the player's attacks.

Stenvor
Stenvor is a Nord found in Winhelm, he can be bought (500) as a mercenary from Candlehearth Hall. He is quite skilled with two-handed weapons, as he mentions when you first meet him. He wears steel armor and has a steel greatsword sheathed on his back.

Faendal
Faendal is a male Bosmer who is initially found by the wood mill in Riverwood, and will return there to wait for you if dismissed. He excels in archery and can train you in Archery up to 5 times per level or until level 50 archery skill is reached.

To get Faendal as your companion, you must complete the quest involving the fake letter from Sven, choosing to reveal the real nature of the letter to Camilla Valerius (i.e. telling her that Sven wanted her to think it came from Faendal). This gains you the gratitude of Camilla as well as Faendal. After completing this quest, you can ask Faendal to follow you and he will readily oblige.

Faendal seems to have a lawful disposition; if you lockpick your way into residences, he will occasionally say, "You should not be in here." Also, if you enter combat with Whiterun guards, he will stop following you and begin attacking you.

Alternatively, you can recruit Sven (Faendal's rival in the love triangle with Camilla), but this is not recommended because Sven is only a bard, whereas Faendal is a trained archer.

Exploit: As a follower as well as a trainer for Archery, you can essentially get Faendal to train you for free; after you pay him for the training, you can ask to trade items with him and take the gold back from his inventory.

Sven
Sven is a male Nord initially found in Riverwood. He is the alternative companion available to you if you choose to lie to Camilla (as he instructs you) and give her the fake letter claiming it is from Faendal.

Lydia
Lydia is a female Nord warrior from Dragonsreach. She becomes available after the revelation of the Dragonborn when Jarl Balgruuf appoints you as Thane and offers her as your Housecarl. When dismissed, she will return to the Jarl's hall and linger near the dining table. If you have purchase Breezehome in Whiterun, she will instead return there.

Note: She is an excellent thief.

Golldir
Golldir is initially found in Hillgrund's Tomb, and can be recruited outside the Tomb after you have helped him kill the warlock Vals Veran.

He is a Warrior who specializes in heavy armor and two-handed weapons.

Uthgerd the Unbroken
Uthgerd is a female Nord who is initially found in the Bannered Mare tavern in Whiterun. Upon meeting her, she will tell you how she was rejected by the Companions of Whiterun for accidentally killing her dueling partner during her initiation test. The Companions dismissed her as having too much "heat and fury".

To recruit her, you must first defeat her in an unarmed brawl. When you dismiss her, she will return to her home in the Cloud district of Whiterun.

Note: She makes an excellent tank.

Jenassa
Jenassa is a female rogue-type Dunmer, initially found in the Drunken Huntsman in Whiterun. She has a lust for killing and advertises her shadowy sensibilities to the player. She is a mercenary and charges 500 septims to recruit each time, unless the player is also Dunmer, in which case she works for free. When dismissed, she lingers in the shadow of the archway between the Wind District and the Cloud District.

Note: As with all mercenaries, after quests which replace your current follower with a required person for the quest, she will have to be re-hired for another 500 septims.

Cicero
Cicero is a male Imperial found in the Dark Brotherhood Questline. If you don't kill Cicero during the quest The Cure for Madness. When you finish the final questline The Dark Brotherhood Forever, and take control of Dawnstar Sanctuary. Leave the sanctuary and there you will find Cicero, happily jumping that you're the listener and becomes your follower.

Borgakh the Steel Heart
Borgakh is a female Orc found in Mor Khazgur. She can be recruited if the player persuades her or pays her dowry.

Kharjo
To access Kharjo, you need to finish a quest outside of Windhelm where you have to find his moon amulet

J'zargo
J'zargo is a male Khajiit found in The College of Winterhold, available after you complete his quest to test his scroll's effects upon three undead.

Vigilance
Vigilance is a canine companion that can be purchased outside the city of Markarth, just inside the stables. He cannot carry items for you but will follow you in a similar manner to any companion. Note: It is possible to have both a canine companion and a humanoid companion simultaneously.

Meeko
Meeko is also a canine companion.

Illia
Illia is a female Imperial found in Darkblight Tower. She can be recruited after you assist her in killing her mother. To prevent spoilers, I will not say anything of her actual storyline besides that you must speak to her after the deed is done. She is a Mage that focuses heavily upon Frost related spells.

Erandur
Erandur is a male Dunmer. He's a priest of Mara, and can be found in the inn in Dawnstar. He's available as a companion, after you solve the problem of nightmares that bother citizens of Dawnstar. During the quest, at one point you'll have a choice whether to let him live, or to kill him. Obviously you can't kill him if you want him to be your companion. He uses destruction magic with one hand while welding a mace in the other, but at times he'll even use a bow.

Marcurio
Marcurio is a male Imperial magician available for hire at the Bee and Barb in Riften for 500 septims.