Ralpacan (T. རལ་པ་ཅན ral pa can), or Ralpachen, born c. 806 CE, was the 41st king of Tibet (Yarlung Dynasty), and the third of the "Three Dharma Kings" of Tibet; the first two were Songtsen Gampo and Trisong Detsen. Ralpachen was the grandson of Trisong Detsen. He reigned from c. 815 until his assasination by his brother in 838.
Ralpachen was a great supporter of Buddhism in Tibet. He built many temples and he invited many scholars from India to Tibet. He was also a skilled political and military leader, and during his reign the Tibetan empire grew to its largest extent.
The assasination of Ralpachen by his brother Langdarma in 838 ended the imperial patronage of Buddhism in Tibet. Langdarma persecuted Buddhism during his reign, and Langdarma's death was followed by civil war and the dissolution of the Tibetan Empire.