Mîm

Mîm (d. FA 502) was a Petty-dwarf of the First Age and possibly the last of the Petty-dwarves. He is mostly a part in the adventures of Turin Turambar.

History
Mîm lived with his two sons at Amon Rûdh in middle Beleriand, where he kept a secret treasury. During Túrin's time with the Outlaws, Mîm and sons were seen as they snuck past the outlaws carrying heavy sacks. Mîm was captured, and arrows were shot at his sons Ibûn and Khîm.

In exchange for his life, Mîm was forced to lead the outlaws to his secret halls in Amon Rûdh. There, it turned out Khîm had been killed by an arrow loosed by Androg, who was then forced to break his bow and arrows, and Túrin repenting offered his service to Mîm. For this reason Mîm tolerated the outlaws, and although he never loved Túrin, the dwarf at least came to respect him.

When Beleg Cúthalion arrived at Amon Rûdh, Mîm was angry: he hated elves, especially the Sindar. Nevertheless he had to tolerate the elf in his halls. This hatred toward Beleg led Mim to betray Amon Rudh to Morgoth. After Amon Rûdh was betrayed to Morgoth, All the outlaws were slain, save Túrin and Beleg. Beleg was left tied up on the summit of Amon Rûdh by the orcs, and there Mîm found him and attempted to kill him but was scared away by a dying outlaw called Andróg. Mîm escaped, but it seems Ibûn was killed by orcs. Eventually Mîm made his way to ruined Nargothrond after Túrin had killed Glaurung, and took the treasure for his own.

Húrin Thallion, who had seen all that had happened to Túrin with Morgoth's eyes, came across Mîm in Nargothrond, and killed him, deeming him partially responsible for Túrin's fate. With his dying words Mîm cursed the treasure. Húrin's band brought the treasure of Nargothrond to Doriath, where eventually the gold was a reason for the Sack of Doriath and the death of Thingol.

Other versions of the legendarium
Note that in the published The Silmarillion Mîm hardly appears. His role is much expanded in the Narn i Chîn Húrin as published in the Unfinished Tales, and in the Wanderings of Húrin.

In earlier versions of the Silmarillion as detailed in The History of Middle-earth series, Mîm was a much more evil character, who actively betrayed Túrin. But as dwarves gradually changed in Tolkien's writings from evil orc-like beings to the dwarves they later became, Mîm's character was changed, and in the final texts he is no longer a true villain, but almost a tragic character in his own right.