Heavy Zed

Heavy Zeds, also referred to as simply Owls, are birds that appear in the Tree Zone of Super Mario Land 2: 6 Golden Coins. They are large owls that are usually seen asleep. Their name is a play on the phrase "heavy sleeper" and "zed", the British English pronunciation of the letter Z, which is commonly used to denote snoring.

Super Mario Land 2: 6 Golden Coins
Heavy Zeds can be used as platforms. When Mario approaches a Heavy Zed, it wakes up, and he can then stand on top of it to be carried to another area. A similar role is served by other owls in later games, such as Hoot from Super Mario 64 and the owls from Wario Land II and Wario Land 3.

Super Mario-kun
A singular Heavy Zed appears in volumes 7 and 10 of Super Mario-kun. While fighting a Battle Beetle, Mario avoids its punch which hits a branch from which a sleeping Heavy Zed falls, without waking up, squashing the Battle Beetle. While keeping it awake, Mario and Carrot fly on its back to reach the Big Bird's nest. Later, seeing them in difficulty, the Heavy Zed brings a bonus bell and, by hitting it, summons a Fire Flower from the Mario Catcher minigame. With the flower, Mario beats the Big Bird and the three then look for the Golden Coin inside the Big Bird's eggs. The Heavy Zed finds it, but falls asleep. In volume 10, after Mario manages to break Wario's hypnosis on the Mario Land inhabitants, Luigi collects the inhabitants and, riding the Heavy Zed, they reach Mario in time to cheer for him as an audience during the final battle.

Super Mario Land 2: 6 Golden Coins

 * Virtual Console manual: This isn't really an enemy; it's a sleeping owl. If Mario climbs onto this owl's head, it'll wake up and give Mario a ride. Heavy Zed has other friends that will give Mario a ride, too.