The forest of Mirkwood was featured heavily in J.R.R. Tolkien's book, The Hobbit, first published in 1937. It was a dark, foreboding place ruled by a merciless elf king who captured Bilbo's traveling companions, the Dwarves, and threw them into his dungeons. Mirkwood was a place full of spiders, treacherous rivers, and an ever-present shadow lying over the entire woodland. In Peter Jackson's second trilogy in The Lord of the Rings universe, The Hobbit film adaptations, he drew the connection between the Elf-prince Legolas and Mirkwood. An alteration to the source material, as Legolas never actually appeared in the book version of The Hobbit.
Source：https://www.cbr.com/lord-of-rings-elves-thranduil-fate/
