Mara is a Sanskrit word meaning "death" or any personification thereof.
In Hinduism, generally, the word "Mara" would be used in the same way that Western popular culture sometimes depicts a grim reaper. This is meant not to represent a literal character that would receive worship or appear in scripture, but rather an active force which acts on people's lives.
References
Mara (Hindu goddess) Wikipedia(Text) CC BY-SA