Philistine
brazen
callous
calloused
case-hardened
cold
cold of heart
coldblooded
coldhearted
conscienceless
flinthearted
flinty
hard
hard of heart
hard-boiled
hardened
heartless
impervious
indurated
insensitive
inured
lost to shame
obdurate
pachydermatous
proof against
seared
shameless
steeled against
steely
stony
stonyhearted
thick-skinned
unblushing
uncompassionate
unemotional
unfeeling
unmerciful
unnatural
unresponsive
unsympathetic
softhearted