A KOALA walked into a bar … no, seriously.

And the bartender on duty at the time hopes he's coming back, because he's good for business.

Kevin Martin, who works at the Marlin Bar on Queensland's Magnetic Island, was stunned when a wild male koala wandered in on Saturday night.

''He sauntered up to the bar, I asked him for ID and he got all disgruntled … walked around the bar and then climbed up a pole and sulked,'' he said. ''We have a big stuffed marlin on the roof and he just sat under the marlin in front of the speaker, listening to the music. He fell asleep.''

Mr Martin said it was a rainy night and the koala might have been trying to get out of the wet.