The Hobbit, or, There and Back Again
King of the Wood-elves
As the narrator says, the elves are "Good People" (8.128). In much the same way that there cannot be a good goblin, there cannot be a truly bad elf. At the same time, the elves and the dwarves don't totally love each other, and let's not forget that we're following the adventures of some dwarves. So elves don't appear in quite the best light in The Hobbit. And the Wood-elves, whom we see the most, are somewhat faulty elves: they "distrust [...] strangers" (8.128), and are really suspicious of poor Thorin and his desperate dwarves.
The main elf whom we meet in The Hobbit (besides Elrond) is the King of the Wood-elves. He captures Thorin and the rest of the dwarves as they wander lost in Mirkwood. Thorin absolutely refuses to explain what he's doing in Mirkwood (because he doesn't want the Elvenking to get any ideas about sharing Thorin's treasure). So the Elvenking locks Thorin in a dungeon to make him learn some manners. What's more, the elf-king has a weakness for treasure: "though his hoard was rich, he was ever eager for more, since he had not yet as great a treasure as other elf-lords of old" (8.129).
Still, even if he is a bit greedy and prejudiced against dwarves, the Elvenking is essentially good. As with all the elves, he's strongly associated with nature: he wears "a crown of berries and red leaves" (9.5) in honor of autumn. And considering the fact that the wicked goblins are associated with mechanical things and engines, the Elvenking's reverence for nature proves that he's a good guy in this context. What's more, when he hears that Lake-town has been destroyed by the body of Smaug, he brings his armies to the city to help. He also joins with Bard in confronting Thorin (a move that doesn't make Thorin particularly happy).
Once the Battle of Five Armies is over, Bard gives the Elvenking a gift of emeralds in thanks for his assistance. And Bilbo, honest to a fault, presents the Elvenking with a necklace made of silver and diamonds to pay for the food he stole from the Elvenking while he was hiding in his cellars – what a guy. The Elvenking agrees and names Bilbo "elf-friend and blessed" for giving this gift (18.49). So everyone comes away happy from the Elvenking's involvement in Bilbo's adventure.