An Undang is a ruling chief or territorial chief who still play an important role in the state of Negeri Sembilan, Malaysia. The name is believed to be derived from the Malay word undang-undang meaning law.
Traditionally, the Minangkabau who settled at Negeri Sembilan, in present-day Malaysia at the end of the 17th Century choose from amongst themselves a "penghulu" or headman. Several of these "penghulus", notably that of Sungai Ujong, Jelebu, Johol and Rembau became powerful enough to exalt themselves above other "penghulus". By the early part of the 18th Century, the leaders of these four districts started calling themselves "Undang".
Malaysia's modern day constitution confirms the status of the Undang under Article 71, 160 and 181 as Malay Ruler within the Federation. Undangs are still chosen from amongst certain noble families in the state, the succession being both matrilineal and elective following the Adat Purbakala.
Chieftains are selected among the nobility in each Luak (chiefdom), following matrilineal inheritance, part of the state's adat perpatih customs.
The senior wife of an Undang has the honorific title of "To' Puan".
The Undangs carry out duties such as co-head of state, co-head of Islam as state religion, upholding and safeguarding Bumiputera special position in Negeri Sembilan, attending the state opening of the legislative assembly and electing the Yang di-Pertuan Besar of Negeri Sembilan, who is also the co-head of state of Negeri Sembilan. The Undangs themselves cannot stand for election and their choice of ruler is limited to a male Muslim who is Malay and also a "lawfully begotten descendant of Raja Radin ibni Raja Lenggang".