The Nicolaitans were followers of Nicolas, one of the seven deacons appointed in Acts 6:5 who later departed from the faith.  His followers lived for pleasure, pursuing luxury, living in immorality, and eating food offered to idols.  According to the early Christians, the Nicolaitans were an early Gnostic sect, later influencing other false teachers.  In Revelation 2:6 (also verses 15-16), Jesus specifically condemned this group and praised the early church for their opposition to these heresies: “You hate the works of the Nicolaitans, which I also hate.”  Read more about Gnosticism here.