Indeed, even Arjuna didn't know appropriately that Krishna was a God before he demonstrated His Mahavishnu Virat Roop. Different characters who realized that Krishna was a God are -

Vyasa - He had divine eyes from which he can undoubtedly become more acquainted with Krishna's Divine reality.

Sanjaya - Before the kurukshetra war vyasa allowed him *Divya chakshva i.e *Divine vision . He additionally observed the Mahavishnu Roop of Krishna .

Vidura-He was an edified man and effectively could separate among Krishna and others.

Bheesma-He additionally realized that who Krishna truly was . At the hour of his deathbed when he was in his bed of bolts Krishna approached him in the event that he stressed for anything , he answered that one who has seen Hari will never be concerned. Krishna just grinned.

Karna - Before the war among Arjuna and Karna he demonstrated his Virat Roop to Karna . Furthermore, yes I feel that before additionally Karna realized that Krishna was God since he never affronted Him , dissimilar to Duryodhana who a few times disparaged Krishna .

Devki and Vasudev - They had a heavenly vision of Lord Vishnu when they were in jail .

Yasoda - The non-permanent mother of Krishna never understood that Krishna could be Narayana until one day , Krishna indicated her the whole universe in His mouth . Yet, , because of Maya she overlooked it and her protective dedication never showed signs of change . She never regarded Krishna as a God.

Kunti - As she was the auntie of Krishna she saw all the *bal Lilas *of Him and accepted all the extraordinary things happens to Vasudev. She was a Bhakta of Krishna.

Gandhari - Gandhari was an extraordinary lover of Lord shiva thus normally she would have divine vision from which she can fathom that Krishna was Lord Himself.

Radha and different Gopikas - obviously they were absolute best to Krishna's heart . They had divine involvement in Krishna a during Ras and acknowledged Krishna was Vishnu.

Balarama - Balrama was AdiShesha thus he would know about the way that Krishna was the manifestation of Vishnu . Different Yadavas like Akrura likewise realized that Krishna was God.

Well , you should give up yourself to God and have full confidence to see Him . Vain person and self-important individuals like Duryodhana couldn't encounter the Divinity of Lord Krishna.

Also Read- What is the essence of Bhagwad Geeta?