Moon Patrol has blue aliens whose bombs create craters. These aliens also love to fly out of range of the moon buggy's aerial blaster, which makes stopping them nearly impossible (in the Atari 2600 version of the game, this tendency promotes them from Bats to Piece of Fecal Material Bats).
Not technically an enemy, but get into first place in a Mario Kart game and you will come to dread any opponent finding a Spiny Shell, a weapon that can be fired from any location on the track to automatically cause the guy in first to wipe out and which is unavoidable unless you have a star (which you can't even get when you're in first). In 64, Super Circuit, and 7 the shell chases its target on the ground with much better homing abilities than a Red Shell and it's possible to get caught in its path even when not in first place, though only whoever's in first is guaranteed to get hit by it. In every other game except Super Mario Kart (which didn't have the item in question), it has wings, so it's harder to get hit by except when in first or when close to whoever is. Starting with Double Dash!!, the shell explodes when it reaches its target (even after the wings were removed in 7), so anyone caught in the blast wipes out as well.
In Double Dash, it's actually possible to dodge if you're playing on Co-Op mode. The "gunner" just has to do a rather precisely timed side-tackle. You can also avoid it if you have three mushrooms or are near boosts, but you have to hit the boosts at just the right time, three times in a row. After that, the shell will veer off course and explode in the distance. A well-timed mini-turbo is also capable of dodging the shell, mostly because the shell has poor turning abilities once it goes in for the kill.
If you get targeted by a Spiny Shell in a level with a cannon you can avoid getting hit if you enter it at the right time... although this does require a lot of luck.
In Mario Kart Wii, you can dodge a Spiny Shell if you have a mushroom (which, unfortunately, you can't get in first place) If you punch it right before the shell dives down to hit you, you will speed ahead out of the blast.
Mario Kart Wii also features literal bats.
In Wario's Gold Mine, they swarm at you by the entrance and push you and slow you down if you get hit by one.
Dry Dry Ruins has bats at the entrance to the temple and one by the big jump as you exit the temple. The ones by the big jump fly towards the ramp and if they touch you in mid air, they can knock you way off course and out of bounds from a simple bump. Goddamned Bats to the max! (Fortunately, the Swoopers in 7 are easier to dodge and less annoying.)
The more-or-less randomly-generated yellow traffic cars in Wangan Midnight Maximum Tune, which are the main reason Maximum Tune is one of the very few competitive racing games in which the catch-up feature is not taboo among players.
Many street racing games (such as the Burnout series, the Shutokou Battle series, and the Wangan Midnight Maximum Tune series, and such) have Traffic that can force you to immediately get out of its way or risk a ruined race. However, traffic can be used in Burnout to your advantage to take down other opponents, and launched into the paths of opponents in Maximum Tune.