en 1.9+ /opps, Mobs & Pets

/summon Zombie ~ ~1 ~ {CustomName:"&f&lSnowMan",CustomNameVisible:1,Attributes:[{Name:"generic.followRange",Base:500},{Name:"generic.attackDamage",Base:0}],Invulnerable:1,ArmorItems:[{},{},{},{id:"minecraft:skull",Damage:3,tag:{SkullOwner:GLaDoS}}],ActiveEffects:[{Id:1,Amplifier:1,Duration:2147483647,ShowParticles:0b},{Id:14,Amplifier:0,Duration:2147483647,ShowParticles:0b}]}