Siyaka (reigned c. 949-972 CE) was an Indian king from the Paramara dynasty, who ruled in west-central India. He was the first independent sovereign of the Paramara royal house, and is the earliest Paramara ruler known from his own inscriptions.
He started out as a feudatory of the Rashtrakutas of Manyakheta, and participated in their campaigns against the Pratiharas. After the death of the Rashtrakuta emperor Krishna III, he fought against the new king Khottiga, and sacked the Rashtrakuta capital Manyakheta in 972 CE. This ultimately led to the decline of the Rashtrakutas, and establishment of the Paramaras as an imperial power.
Siyaka is also referred to as Siyaka II to distinguish him from Siyaka I, an earlier (and possibly fictional) Paramara king mentioned in the later Udaipur Prashasti inscription. His other names include Harsha, Sri-Harshadeva and Simhabhata.