Little Moe Szyslak is a student at Springfield Elementary School who looks like a child version of Moe Szyslak and has a voice identical to Moe's. When Martin Prince and Database find a note on their lockers signed LMS (later revealed to be Lisa Simpson) they think "Little Moe" may have written it. He gets angry and walks away. He also appeared in Treehouse of Horror V and is seen sitting in the same table as Jimbo.
His appearance suggests he is a relative of Moe Szyslak. If there is a relation, it would likely be an extended one, because he doesn't understand why people keep calling him Little Moe Szyslak, as if he does not know who Moe Szyslak is.