The meme characters are minor characters on Edgy Oobi.
The meme characters are, obviously, characters and people from internet memes of the past and present. They are used most often in cutaway gags in the series. In the first episode, "Oobi Gets Addicted to Memes," the meme characters are actually important to the plot. In that episode, Oobi gets addicted to them and browses every meme in existence.
What they look like varies a lot depending on the meme. If you really want to know what they look like, Google any of the memes listed below.
The following meme characters/people have made appearances: