who are the major Gods in Hinduism?

Give me at the most 5.

1. Krishna

Brahma, Vishnu, and Shiva are the biggest ones you need to know and understand.

Brahman or Brahma, is the "God" everything comes from. Atleast in Advaita Vedanta Hinduism.

As for "mainstream Gods", I would say, Vishnu (incarnate of Krishna), Devi (Sita, Parvati, Kali etc), Ganesh (son of Parvati/Devi), Shiva..?

Those are the ones I can think of right now.

The "Big Three" are Brahma, Vishnu, and Shiva. They are the creator, sustain er, and destroyer, respectively. Indra used to be the numeric uni, as it were, but his prominence has waned. Also worth mention are Yama, the god of death/justice; Agni, the god of fire; Ganesha, the remover of obstacles; Parvati, the wife of Shiva and a "Divine Mother" figure; and Kali, the goddess of time and change.

(Krishna is simply an incarnation of Vishnu, kind of similar to a Jesus figure. Hare Krishna is an offshoot of Hinduism centered around him.)

Sorry, more than five.

remember Hinduism is technically monotheist. There is only one god. however he is so great that he has many forms (330mill) each describing his qualities i.e Ganesha represents intellect. he has many forms yet he is formless. Hindus however considers his main forms to be the Trimurti Brahma, Vishnu and Marsh. Lets us not however forget about dugGAa.