The most fundamental of Hindu deities, is the Trinity of Brahma, Vishnu and Shiva - popular deities include Ganesha, Krishna, Hanuman and goddesses like Lakshmi, Durga,Saraswati.
Demons killed by Krishna
Srila Bhaktivinoda Thakura in his Sri Caitanya Siksamrita describes the demons Krishna killed in His Vrindavana pastimes and the anarthas (unwanted things) that they represent.
In all the cases listed, Krishna is not killing a demon.
Putana - the pseudo guru
Sakatasura (the cart demon) - carrying the burden of a cart-load of old and new bad habits, lethargy and vanity.
Trinavarta (the whirlwind demon) - false pride which comes from material scholarship, which leads to bogus philosophies.
Deliverance of Nalakuvara and Manigriva (breaking the twin arjuna trees) - Arrogant pride which comes from puffed-up prestige, which is rooted in a madness for wealth.
Vatsasura (the calf demon) - a childish type of mentality which gives rise to a type of greediness which results in a wicked type of mischievousness.
Bakasura (stork demon) - Cunning duplicity, deceptiveness and false types of behavior.
Aghasura (the snake demon) - Cruelty and violence.
Brahma-vimohana Pastime (Lord Brahma steals the cowherd boys and calves) - mundane activities and speculative scholasticism.
Dhenukasura (the ass demon) - gross materialistic intelligence, ignorance of spiritual knowledge.
Kaliya (chastising the Kaliya serpent) - brutality and treachery.
Extinguishing the Forest Fire - inter-communal discord among Vaishnavas.
Pralambasura (killing the Pralamba demon) - lusty inclinations; desire for personal gain and honor.
Second Forest Fire - disturbance of religious principles and interference with religious people who are atheist.
Brahmanas Performing Sacrifice - indifference toward Krishna caused by pride because of one's status (position) in varnasrama.
Overcoming the Pride of Indra - demigod worship, and the tendency to think "I am Supreme."
Nanda Maharaja Captured by Varuna - thinking that spiritual life can be enhanced by intoxication.
Nanda Maharaja Swallowed by Vidyadhara (the snake) - rescuing the truth of Krishna consciousness from being swallowed by the impersonalists. Sankhacuda (killing the conch-shell demon and getting the jewel that was stolen by him) - proneness toward acquiring name and fame, and desire for sensuous enjoyment, under the plea of devotion.
Aristasura (the bull demon) - pride arising from indulging in false religions invented by cheaters which causes neglect of devotional service (bhakti).
Kesi (the horse demon) - The feeling that "I am a great devotee and spiritual master."
Vyomasura (the demon in the sky) - associating with thieves and other rascals, and with people who put themselves forward as avataras.