A demoness, servant of Kamsa, he sent her to kill Krishna. She smeared her nipples with poison and breastfed him, Krishna sucked her life from her.
Putana was in her previous life Ratnamala, sister of Bali. When Vishnu appeared as a dwarf, she was so entranced by the ‚child‘ that she wanted to breastfeed it. Vishnu promised her to do this in her next life.