The Little Egret (Egretta garzetta) used to be a very rare vagrant in Iceland but  in recent years they have been seen more often. The birds that come to Iceland probably come from Great Britain or Ireland where their numbers have been increasing in the last 20 years.

This guy was taking a stroll by the River Ölfusá in October. It is the first Little Egret that I see this year and probably the second bird to be seen in Iceland this year.

More information on the Little Egret
https://www.rspb.org.uk/discoverandenjoynature/discoverandlearn/birdguide/name/l/littleegret/