Let's handle (bwhaha) the Craft* entities a bit better.

src/main/java/org/bukkit/craftbukkit/entity/CraftAnimals.java

@@ -4,7 +4,7 @@ import net.minecraft.server.EntityAnimal;
 import org.bukkit.craftbukkit.CraftServer;
 import org.bukkit.entity.Animals;
 
-public class CraftAnimals extends CraftCreature implements Animals{
+public class CraftAnimals extends CraftCreature implements Animals {
 
     public CraftAnimals(CraftServer server, EntityAnimal entity) {
         super(server, entity);
@@ -15,4 +15,8 @@ public class CraftAnimals extends CraftCreature implements Animals{
         return "CraftAnimals";
     }
 
+    @Override
+    public EntityAnimal getHandle() {
+        return (EntityAnimal) entity;
+    }
 }

src/main/java/org/bukkit/craftbukkit/entity/CraftCreature.java

@@ -7,34 +7,30 @@ import org.bukkit.entity.Creature;
 import org.bukkit.entity.LivingEntity;
 
 public class CraftCreature extends CraftLivingEntity implements Creature{
-    private EntityCreature entity;
-
     public CraftCreature(CraftServer server, EntityCreature entity) {
         super(server, entity);
-        this.entity = entity;
     }
 
     public void setTarget(LivingEntity target) {
+        EntityCreature entity = getHandle();
         if (target == null) {
             entity.d = null;
         } else if (target instanceof CraftLivingEntity) {
-            EntityLiving victim = ((CraftLivingEntity)target).getHandle();
+            EntityLiving victim = ((CraftLivingEntity) target).getHandle();
             entity.d = victim;
             entity.a = entity.world.a(entity, entity.d, 16.0F);
         }
     }
 
     public CraftLivingEntity getTarget() {
-        if (entity.d == null) {
-            return null;
-        } else {
-            return (CraftLivingEntity)entity.d.getBukkitEntity();
-        }
+        if (getHandle().d == null) return null;
+
+        return (CraftLivingEntity) getHandle().d.getBukkitEntity();
     }
 
     @Override
     public EntityCreature getHandle() {
-        return entity;
+        return (EntityCreature) entity;
     }
 
     @Override

src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java

@@ -10,7 +10,7 @@ import org.bukkit.util.Vector;
 
 public abstract class CraftEntity implements org.bukkit.entity.Entity {
     protected final CraftServer server;
-    private Entity entity;
+    protected Entity entity;
 
     public CraftEntity(final CraftServer server, final Entity entity) {
         this.server = server;

src/main/java/org/bukkit/craftbukkit/entity/CraftHumanEntity.java

@@ -9,22 +9,20 @@ import org.bukkit.craftbukkit.inventory.CraftItemStack;
 import org.bukkit.craftbukkit.CraftServer;
 
 public class CraftHumanEntity extends CraftLivingEntity implements HumanEntity {
-    private EntityHuman entity;
     private CraftInventoryPlayer inventory;
 
     public CraftHumanEntity(final CraftServer server, final EntityHuman entity) {
         super(server, entity);
-        this.entity = entity;
         this.inventory = new CraftInventoryPlayer( entity.inventory );
     }
 
     public String getName() {
-        return entity.name;
+        return getHandle().name;
     }
 
     @Override
     public EntityHuman getHandle() {
-        return entity;
+        return (EntityHuman) entity;
     }
 
     public void setHandle(final EntityHuman entity) {

src/main/java/org/bukkit/craftbukkit/entity/CraftLivingEntity.java

@@ -23,15 +23,12 @@ import java.util.ArrayList;
 import java.util.Iterator;
 
 public class CraftLivingEntity extends CraftEntity implements LivingEntity {
-    private EntityLiving entity;
-
     public CraftLivingEntity(final CraftServer server, final EntityLiving entity) {
         super(server, entity);
-        this.entity = entity;
     }
 
     public int getHealth() {
-        return entity.health;
+        return getHandle().health;
     }
 
     public void setHealth(int health) {
@@ -39,12 +36,12 @@ public class CraftLivingEntity extends CraftEntity implements LivingEntity {
             throw new IllegalArgumentException("Health must be between 0 and 200");
         }
 
-        entity.health = health;
+        getHandle().health = health;
     }
 
     @Override
     public EntityLiving getHandle() {
-        return entity;
+        return (EntityLiving) entity;
     }
 
     public void setHandle(final EntityLiving entity) {
@@ -59,14 +56,14 @@ public class CraftLivingEntity extends CraftEntity implements LivingEntity {
 
     public Egg throwEgg() {
         net.minecraft.server.World world = ((CraftWorld)getWorld()).getHandle();
-        EntityEgg egg = new EntityEgg(world, entity);
+        EntityEgg egg = new EntityEgg(world, getHandle());
         world.a(egg);
         return (Egg) egg.getBukkitEntity();
     }
 
     public Snowball throwSnowball() {
         net.minecraft.server.World world = ((CraftWorld)getWorld()).getHandle();
-        EntitySnowball snowball = new EntitySnowball(world, entity);
+        EntitySnowball snowball = new EntitySnowball(world, getHandle());
         world.a(snowball);
         return (Snowball) snowball.getBukkitEntity();
     }
@@ -120,30 +117,30 @@ public class CraftLivingEntity extends CraftEntity implements LivingEntity {
 
     public Arrow shootArrow() {
         net.minecraft.server.World world = ((CraftWorld)getWorld()).getHandle();
-        EntityArrow arrow = new EntityArrow(world, entity);
+        EntityArrow arrow = new EntityArrow(world, getHandle());
         world.a(arrow);
         return (Arrow) arrow.getBukkitEntity();
     }
 
     public boolean isInsideVehicle() {
-        return entity.vehicle != null;
+        return getHandle().vehicle != null;
     }
 
     public boolean leaveVehicle() {
-        if (entity.vehicle == null) {
+        if (getHandle().vehicle == null) {
             return false;
         }
 
-        entity.setPassengerOf(null);
+        getHandle().setPassengerOf(null);
         return true;
     }
 
     public Vehicle getVehicle() {
-        if (entity.vehicle == null) {
+        if (getHandle().vehicle == null) {
             return null;
         }
 
-        org.bukkit.entity.Entity vehicle = (entity.vehicle.getBukkitEntity());
+        org.bukkit.entity.Entity vehicle = (getHandle().vehicle.getBukkitEntity());
         if (vehicle instanceof Vehicle) {
             return (Vehicle) vehicle;
         }
@@ -152,18 +149,18 @@ public class CraftLivingEntity extends CraftEntity implements LivingEntity {
     }
 
     public int getRemainingAir() {
-        return entity.airTicks;
+        return getHandle().airTicks;
     }
 
     public void setRemainingAir(int ticks) {
-        entity.airTicks = ticks;
+        getHandle().airTicks = ticks;
     }
 
     public int getMaximumAir() {
-        return entity.maxAirTicks;
+        return getHandle().maxAirTicks;
     }
 
     public void setMaximumAir(int ticks) {
-        entity.maxAirTicks = ticks;
+        getHandle().maxAirTicks = ticks;
     }
 }

src/main/java/org/bukkit/craftbukkit/entity/CraftMonster.java

@@ -16,4 +16,8 @@ public class CraftMonster extends CraftCreature implements Monster {
         return "CraftMonster";
     }
 
+    @Override
+    public EntityMonster getHandle() {
+        return (EntityMonster) entity;
+    }
 }

src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java

@@ -18,13 +18,10 @@ import org.bukkit.craftbukkit.TextWrapper;
 import org.bukkit.entity.Player;
 
 public class CraftPlayer extends CraftHumanEntity implements Player {
-    private EntityPlayer entity;
     private String name;
 
     public CraftPlayer(CraftServer server, EntityPlayer entity) {
         super(server, entity);
-        this.name = getName();
-        this.entity = entity;
     }
 
     public boolean isOp() {
@@ -46,7 +43,7 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
     }
 
     public InetSocketAddress getAddress() {
-        SocketAddress addr = entity.a.b.b();
+        SocketAddress addr = getHandle().a.b.b();
         if (addr instanceof InetSocketAddress) {
             return (InetSocketAddress) addr;
         } else {
@@ -56,7 +53,7 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
 
     @Override
     public EntityPlayer getHandle() {
-        return entity;
+        return (EntityPlayer) entity;
     }
 
     public double getEyeHeight() {
@@ -82,7 +79,7 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
 
     public void sendMessage(String message) {
         for (final String line: TextWrapper.wrapText(message)) {
-            entity.a.b(new Packet3Chat(line));
+            getHandle().a.b(new Packet3Chat(line));
         }
     }
 
@@ -122,15 +119,15 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
     }
 
     public void kickPlayer(String message) {
-        entity.a.a(message == null ? "" : message);
+        getHandle().a.a(message == null ? "" : message);
     }
 
     public void setCompassTarget(Location loc) {
-        entity.a.b(((Packet) (new Packet6SpawnPosition(loc.getBlockX(), loc.getBlockY(), loc.getBlockZ()))));
+        getHandle().a.b(((Packet) (new Packet6SpawnPosition(loc.getBlockX(), loc.getBlockY(), loc.getBlockZ()))));
     }
 
     public void chat(String msg) {
-        entity.a.chat(msg);
+        getHandle().a.chat(msg);
     }
 
     public boolean performCommand(String command) {
@@ -142,6 +139,7 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
         WorldServer oldWorld = ((CraftWorld)getWorld()).getHandle();
         WorldServer newWorld = ((CraftWorld)location.getWorld()).getHandle();
         ServerConfigurationManager manager = server.getHandle();
+        EntityPlayer entity = getHandle();
 
         if (oldWorld != newWorld) {
             manager.c.k.a(entity);
@@ -168,21 +166,21 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
             manager.b.add(newEntity);
 
             entity.a.e = newEntity;
-            entity = newEntity;
+            this.entity = newEntity;
         } else {
             entity.a.a(location.getX(), location.getY(), location.getZ(), location.getYaw(), location.getPitch());
         }
     }
 
     public void setSneaking(boolean sneak) {
-        entity.b(sneak);
+        getHandle().b(sneak);
     }
 
     public boolean isSneaking() {
-        return entity.U();
+        return getHandle().U();
     }
-    
+
     public void updateInventory() {
-        entity.l();
+        getHandle().l();
     }
 }

src/main/java/org/bukkit/craftbukkit/entity/CraftSheep.java

@@ -7,24 +7,26 @@ import org.bukkit.craftbukkit.CraftServer;
 import org.bukkit.entity.Sheep;
 
 public class CraftSheep extends CraftAnimals implements Sheep {
-
     public CraftSheep(CraftServer server, EntitySheep entity) {
         super(server, entity);
     }
 
+    @Override
+    public EntitySheep getHandle() {
+        return (EntitySheep) entity;
+    }
+
     @Override
     public String toString() {
         return "CraftSheep";
     }
 
     public DyeColor getColor() {
-        EntitySheep entity = (EntitySheep) getHandle();
-        return DyeColor.getByData((byte) entity.n());
+        return DyeColor.getByData((byte) getHandle().n());
     }
 
     public void setColor(DyeColor color) {
-        EntitySheep entity = (EntitySheep) getHandle();
-        entity.a_(color.getData());
+        getHandle().a_(color.getData());
     }
 
 }