Valiathan / Vallyathan is a title held by a group of families, all branches along the matrilineal line of the main Valiathan family known as Vattaparambil valiathan. . It is said that the Maharajah Marthanda Varma of Travancore sought the help of this Vattaparambil family which was duly given to overcome the powerful clan of Ettuveetil Pillamar. The maharajah and the heir apparent, the popular Dharmarajah, therefore addressed the senior most lady of the Vattaparambil House as Valiyamma. Later the lord of the Vattaparambil House died in battle on the Travancore side with the Ettuveetil Pillamar.

When Marthanda Varma finally became king, he gave the title of "Valia than " to the Vattaparambil family.

The Vattaparambil family is based in Keerikad ( Fort Vattaparambil)They also have branches in Thiruvalla and Pandalam The Thiruvalla Branch had marital relations with the Nedumpuram royal family there while the Pandalam Family, known as Thottathil, had relations with the Royal family of Pandalam.

Today these three families, known as the Valiathans, constitute a subcaste of the Nair community. They are not permitted to intermarry as they are matrilineal branches of the same family under the Marumakkathayam law.

Valiathan/ Vallyathan is a surname. Notable people with the surname include: