Skien is a town and municipality in the county of Telemark, Norway.

Skien was probably founded as a meeting place for inland farmers and sailing traders, and also as a shipping harbour for whetstones from Eidsborg (inland Telemark). Settelement can be traced back to the 11th century, and the Gimsøy Convent was founded in the 12th century. Skien was given formal commercial town rights by the Danish crown in 1358. Timber has historically been the most dominant export product from Skien.

Skien was connected to the Norwegian railway network in 1882 (Vestfoldbanen). The current town layout was fixed after the last town fire in 1886. In 1964, the rural municipalities Solum and Gjerpen were merged together with Skien town, forming the Skien municipality.

Skien is currently the administrive centre of Telemark County.

The largest industries are

• ABB (electromechanical)
• Norske Skog Union (paper mill)

Other important places of work are

• Telemark Sentralsykehus (hospital)
• Fylkesmannen (The local Norwegian State Administration)

The daily newspapers Varden and Telemarksavisa are published in Skien. Skien harbour is located at Vold havneterminal. Skien airport is called Geiteryggen and serves domestic flights.

Oldest building: Gjerpen church (built approximately 1150)

Highest mountain: Skårrafjellet (814 m ASL)

Telemark Museum is located in Skien. Skien was the birth place of the author and playwright, Henrik Ibsen. At Venstøp in Skien you can find the Venstøp Farm, established as the Ibsen Museum in 1958.