Shallas are a race of incredibly small aliens who, apparently, worship Raven. They Debuted in the episode Stranded. The name of their race is from a word in their language(possibly the equivalent to saying "Amen") that they say after repeating whatever Raven says. They are last seen pampering Raven by fanning, feeding and massaging her.
"Don't go away! Don't go away! Don't go away!" Then-you guessed it-"Shalla!"