Sinha is a surname which originates in the Indian subcontinent. The surname is commonly used by many communities including the Bengali Kayastha and the Chitraguptavanshi Kayasthas of the Hindi Belt, and is common in India, Sri Lanka, and Bangladesh. It comes from a Sanskrit word meaning "lion" or "brave person".

In India, Sinha is commonly used as a surname by the Kayasthas of the West Bengal and Bihar.

In Sri Lanka, the term 'Sinha' (or Siha / Sinhe / Singhe / Singha / Singho) have commonly been used by the Sinhalese (or Sinhala). When it comes to the term 'Sinhala' itself, the first part of the word, 'Sinha' stands for lion while 'la' or 'le' stands for blood, giving the meaning 'Lion's blood'. The word Simhmam (or Singam / Singham / Singhai / Singai) is the Sri Lankan Tamil derivative. In northeast India, Sinhas held high positions as advisors during the times of the Mughal Empire. In northern and middle part of India as well as southern India Sinhraj/Sinharaj/Sinharaja or Rajasinha is also used, having the meaning Lion/Leo king.

The more common surname Singh in India has the same root. Jayasinghe and other surnames like 'Wijesinghe', 'Weerasingha', 'Edirisinghe', 'Singaiariyan' in Sri Lanka may also share this root.

Sinha is also an unrelated name found in Brazil. "Sinhá moça" is a Brazilian colloquialism that may be translated "miss" or "missy".