NET

4 The Nephilim were on the earth in those days (and also after this) when the sons of God would sleep with the daughters of humankind, who gave birth to their children. They were the mighty heroes of old, the famous men.

Darby

4 In those days were the giants on the earth, and also afterwards, when the sons of God had come in to the daughters of men, and they had borne [children] to them; these were the heroes, who of old were men of renown^D63.

Darby Bible Notes

renown - Or 'the name,' i.e. who had a peculiar and known name on the earth. Heroes is Gibbor in Heb., meaning 'mighty men.'

KJV

4 There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare [children] to them, the same [became] mighty men which [were] of old, men of renown.