Hara is one among the numerous names of Shiva. Hara means the ravisher and He got the name after the unimaginable destruction caused by Shiva Ganas at Daksha Yajna.
On hearing about Goddess Sati’s immolation at Daksha’s yajna, Shiva plucked a hair from his head, threw it down, and from it appeared Virabhadra and Bhadrakali.
Unimaginable anger overpowered Shiva and he produced fever and numerous other diseases.
Virabhadra summoned ghosts, goblins, demons and they along with millions of Ganas of Shiva attacked the yajna of Daksha.
Bhadrakali finally beheaded Daksha.
Shiva arrived to witness the death and destruction at Daksha Yajna. Now He was Hara, the ravisher.
However, this fury subsided soon and Shiva became Shankara, the benevolent one.