Chest Pet by jvssmith

/summon MinecartChest ~ ~1 ~ {CustomName:"Companion Chest",CustomNameVisible:1,Invulnerable:1,Riding:{id:"Wolf",Owner:JVSsmith,Attributes:[{Name:generic.maxHealth,Base:100},{Name:generic.attackDamage,Base:-1},{Name:generic.followRange,Base:100}],Invulnerable:1,HealF:100,PersistenceRequired:1,Silent:1}}'

...You'll need to tame it :)