Heavy Zeds, also referred to as simply Owls, are bird creatures found in the Tree Zone of Super Mario Land 2: 6 Golden Coins. They can be used as platforms to reach high places. When Mario approaches one, he will wake up, and then and only then can he use one as a ride. The top of the owl's head is flat, making him an ideal platform for Mario to stand on while being flown to a higher area.
Heavy Zeds' name comes from the common image in cartoon iconography of someone sleeping with a trail of Zs next to them, and "heavy sleeper", meaning one who sleeps soundly and is hard to wake up. Also, since they are large enough for Mario to stand on, the "heavy" part of their name could be a reference to their weight.
Names in other languages