Ralpacan (Tibetan: རལ་པ་ཅན, Wylie: ral pa can), born Tritsuk Detsen (Tibetan: ཁྲི་གཙུག་ལྡེ་བཙན, Wylie: khri gtsug lde btsan) c. 806 CE, the Year of the Dog, was, according to traditional sources, the 41st King of Tibet, ruling from the death of his father, Sadnalegs, in c. 815, until 838 CE. He is referred to as "son of God" in the Testament of Ba.

He was the second of five brothers. The eldest, Prince Tsangma (Wylie: lha sras gtsang ma), took Buddhist vows. The third, Langdarma, who was anti-Buddhist and ruled after the death of Ralpacan, is referred to in the sources as "unfit to reign". The younger two brothers both died young.

Ralpacan is considered very important to the history of Tibetan Buddhism as one of the three Dharma Kings (chosgyal) — Songtsän Gampo, Trisong Detsen, and himself — who brought Buddhism to Tibet. Trisong had five wives, all from Tibetan noble families.

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