The Falathrim were the shoreland Elves of the Falas who took Círdan as their lord from the beginning. Their last home on Middle-earth before finally leaving for the Undying Lands was the Grey Havens, but before that they dwelt mainly in the ancient havens of Eglarest and Brithombar.
In ancient days, the Teleri dwelt for long years in Beleriand, and they learned much from Ossë, a Maia of the Sea. When Ossë's master Ulmo conducted the most part of the Teleri into the West, Ossë persuaded some few to remain behind. They settled on Beleriand's western shores, building themselves Havens at Brithombar and Eglarest. Círdan was their leader, and they were known as the Falathrim, or Elves of the Falas, the first builders and sailors of ships in Middle-earth's history.
After the Return of the Noldor, the Elves of the Falas became fast in friendship with the Deep Elves. With Finrod's aid, the Havens of the Falas were strengthened and rebuilt. The Elves of the Havens enjoyed peaceful relations with all the Elves of Beleriand, and were particularly closely allied with the people of Nargothrond. As one of the most remote peoples from Morgoth's forces in Angband, the other Elvish lords would often send their children to the Elves of the Havens for safekeeping.
They fought beside the Noldor, too: in the Dagor Bragollach ("Battle of Sudden Flame"), their mariners rescued High King Fingon from overwhelming hordes in Hithlum, and they went to the aid of Fingon again at the Nirnaeth Arnoediad ("Battle of Unnumbered Tears"). After that disaster, many of the survivors fled back to the Havens of the Falas, but they were not safe there for long. A year after the great defeat, Morgoth sent his creatures to besiege them, and both the Havens were overthrown. Most of the Elves of the Falas perished in the fall of the Havens, or were captured, but Círdan escaped. With his surviving followers and the young Ereinion Gil-galad, who was at that time lodging with the people of the Havens, he sailed southwards, and settled for a time on the Isle of Balar. He maintained a haven there for many years, before removing once again to Lindon, where he dwelt at the Grey Havens with, doubtless, a remnant of the Falathrim.
Another name for the Falathrim was the Egladhrim, or the Eglain, a Sindarin name meaning "The Forsaken". While originally used as a name for the Sindar by themselves, it came to refer only to the Elves of the Falas, as distinguished from the "inland Elves" of Beleriand.