Is koala a word in Scrabble?

Yes, koala is a word in Scrabble, it is valid in official Scrabble dictionaries including NASPA Word List and Collins Scrabble Words, worth 9 points with K=5, O=1, A=1, L=1, A=1, and is commonly played as animal name. Koala is marsupial native to Australia known for eucalyptus diet, and its name is accepted as common noun in English dictionaries, so allowed in Scrabble. It is 5-letter word, useful for using K high-value tile, similar to strategic placement of high-value items in organized system. Koala is valid in both US and UK Scrabble, with no special restrictions, though plural koalas also valid. Some animal names are not valid if considered proper nouns, but koala is common noun, not proper noun, so allowed. So yes, koala is valid Scrabble word, 9 points before premium squares, and can be extended with S for 10 points, useful for bingo if combined with other letters. So koala is valid word in Scrabble, recognized by official word lists, and playable.