The antonyms of the word party crashers could be invited guests, legitimate attendees, welcomed visitors, authorized entrants, and acceptable companions. Invited guests are those who have received official invitations to the party and are expected to attend. Legitimate attendees are people who have a genuine reason to be at the party, such as colleagues, friends, and family members. Welcomed visitors are those who are welcomed by the host of the party, upon arrival. Authorized entrants are people who have been granted permission to attend the party, such as security personnel, catering staff, and performers. Lastly, acceptable companions are those who are compatible with the party's theme, vibe, and atmosphere.