uninvited

Etymology 1

un- + invited

adj

1. Not invited.
   But you, you're not allowed / You're uninvited / An unfortunate slight 1997, Alanis Morissette (lyrics and music), “Uninvited”, performed by Alanis Morissette

noun

1. (rare) One who was not invited.
   The uninvited came to a Twilight concert! He was old and gray and blase and a cynic. 1917 April, Charme Seeds, “School Activities and the College Girl”, in The Ohio State University Monthly, volume 8, number 9, page 38
   In the future, if you know that you're going to be mixing inviteds and uninviteds while out, call them all ahead of time to caution the inviteds against talking about the wedding and to tell the uninviteds about your guest list so they know you didn't forget about them […] 2011, Sam Scholfield, Awkward.: What to Do When Life Makes You Cringe-A Survival Guide
   As if the uninvited was trying to escape from pain and that truth of that the lake's waters turned black because of her presence. 2020, Natali Stoyanov, translated by Ingrid Turis, The forest’s legends

Etymology 2

From uninvite.

verb

1. simple past and past participle of uninvite