The word Siddhar (or Cittar ) refers to a "perfected individual" who has attained , or supernatural spiritual powers. Historically, the tradition identifies 18 Main Siddhars (Pathinen Siddhargal), though hundreds of others have contributed to the corpus of work.
If you are looking to download and study these texts, several seminal works serve as the foundation of the tradition: List of 18 Siddhars in Tamil | PDF | Travel | Art - Scribd siddhar books in tamil pdf
Discovering the Wisdom of the Ages: A Guide to Siddhar Books in Tamil (PDF) The word Siddhar (or Cittar ) refers to