THIS IS YOUR FIRST AND LAST WARNING. MINOR SPOILERS MAY BE INCLUDED WITHIN THE LIST. (Though if you're up-to-date with the most recent chapter, there won't be any problems.)
Lina Inverse: Cute, coy, and very cunning - this is the main heroine of TSLOD and the anime it was based upon. With a head of steel (sometimes literally) and an unrelenting temper, she rushes forward towards new adventures in life.
Xelloss: Cute, coy, and even more cunning - this is the main hero of TSLOD and a character of priority in the anime. Always keeping his true motives hidden, he finds himself crossing paths with Lina Inverse time and time again.
Gourry Gabriev: Lina's "guardian-of-sorts" who has been the target of her affection for years. Whether he returns her feelings or not is a mystery, but he is a good person who cares for her happiness and well-being.
Zelgadiss Greywers: A character that often radiates contempt and scorn for those around him, but finds a home within the group of travelers. He cares a lot for his companions, although he doesn't always show it in the best way.
Amelia wil Tesla Saillune: A princess who often preaches justice to those around her. Although she may strike you as the happy-go-lucky kind, she actually shows a lot of compassion towards her friends.
Deep Sea Dolphin: A mazoku sub-lord serving under the mazoku lord, Shabranigdu. Her motives are unclear, but she shows interest in our group.
Greater Beast Zelas Metallium: Another mazoku sub-lord serving under Shabranigdu. As she is Xelloss's creator and master, she values him greatly and depends on him to accomplish the missions, which she assigns to him, quickly and thoroughly.
Ramadeus (Prequel): One of Lina's contractors who refused to pay her money for her "work". Not a particularly important character.
Fayle (Prequel): The captain of the fourth squad of golden dragons. Fayle approaches Gourry and Lina in an attempt to recruit them for their cause in the upcoming war between the ryuuzoku and mazoku, but Lina has different thoughts on joining after experiencing the coldness in the way the dragon deals with things.
Rosette (aka Rosa) (1): A strange girl who appeared in the town of Miran shortly after our heroes' arrival. She seems to know a lot about them, but as to why...
Nadesico (1): A girl who has only been briefly aforementioned in the fanfic thus far. More information about her will be known as time progresses.
Violet (1): Another girl who has only been briefly mentioned in the plot.
Tsunami (1): Appearing as a simple town mayor-of-sorts, she invites our travelers in for a meal and celebration. But appearances can be deceiving, and she is certainly no exception to the rule...
Tsurugi (1): A seemingly calm and gentle creature, she appears to be of no threat to the Slayers. But as things progress, circumstances may change...
Miran (1): A faerie who descended from the heavens and founded a town to be named after her. Although the common myth implied a happy ending, it turns out to be a simple cover-up of the real story behind her death...
Hattari (1): A mazoku encountered by Miran after her descent to earth. He seems to be a simple fellow at first, but as his name implies, it may all be one deceiving facade...
Lina du Mar LíCiel (2): Reborn...
Prince Elliot XIII Clyd Zelphia(2): Young handsome Prince Elliot from the neighboring kingdom of Zelphia, destined to wed Princess Lina. There's more to him than meets the eye, though.
King Frederick van Líciel (2): Lina's father in Arc Two and the king of Elsmaria. Despite appearances, he genuinely cares for his daughter and wishes to see her become a queen revered and loved by her people.
Elinor Marcine Rucella(2): The strictest of Lina's maid-servants. She is the pinnacle of the group of maids given the strenuous job of looking after the princess, and she is the only one who can successfuly detain and put the princess in her place. One of Amelia's very distant descendants.
Helena Grace (2): Elinor's right-hand. She's much kinder than Elinor is, and wishes solely for Lina's well being. A pure character throughout.
Gabriel Silverhand (2): One of the two siblings that Lina regularly spends afternoons with. He seems to follow in his father's footsteps, taking a liking to sword and weapon smithing.
Sophia Silverhand (2): The younger of the two siblings. She constantly worries for her brother and takes the responsible role, always reminding Lina and Gabriel when they are stepping out of line, though usually she eventually gets dragged in anyway.
"The Guardian Angel" (2): A mysterious figure who appears before Lina at random times. Not much is known about him, yet, but apparently he recognizes the jewel on her necklace.
Cless (2): Lina's tutor, combat instructor, and friend. He appears not to have a last name, but who is to say that Cless is his real name?
Lynne Fye (2): The third of the three maids who attend to Lina. She's the newest addition and seems to be a bit aloof. She seems to have other matters to tend to, though...
Lanazra (2): A mazoku who is quite frightening in appearance. Her ability allows her to tamper with the dreams and memories of humans.