This article is about the fictional river Gladden. You may have been looking for an article on Washington Gladden, an advocate of the Social Gospel movement.

In J. R. R. Tolkien's fictional universe of Middle-earth, the River Gladden was a river of Rhovanion and a tributary to the Anduin.

Called Sîr Ninglor (River Goldwater) by the Elves, the Gladden was a short but important river of the Vales of Anduin. Beginning as two unnamed arms in the Hithaeglir, it flowed westwards to the Great River Anduin, which it met in a series of marshes called the Gladden Fields.

After the Last Alliance of Elves and Men, Isildur, heir of Elendil and bearer of the One Ring, was assailed by Orcs near the Gladden Fields, and the One Ring was lost here in the Gladden river.

Much later during the Third Age some Stoors lived near the streams of Gladden, and from them came Déagol who found the ring, was killed by Sméagol (Gollum), who long held the Ring. Gollum eventually followed the stream up to its source, ending up in forgotten caves near Goblin Town.

Saruman searched the Gladden extensively during his search for the Ring, but never found the ring, although he seems to have found Isildur's remains.