bowelless
cutthroat
fierce
mortal
pitiless
remorseless
ruthless
tigerish
unpitying
barbarous
brutal
brutish
callous
calloused
cold
cold of heart
coldblooded
coldhearted
cruel
dog-eat-dog
flinthearted
flinty
hard
hard of heart
hardened
hardhearted
harsh
heartless
inclement
inexorable
inhuman
insensitive
mean
merciless
obdurate
relentless
savage
stonyhearted
uncompassionate
uncompassioned
unfeeling
unforgiving
unkind
unnatural
unpitiful
unremorseful
unresponsive
unsparing
unsympathetic
unsympathizing
unyielding
covetous
hard-hearted
inhumane
iniquitous
judgmental
perfidious
revengeful
tyrannical
uncalled-for
uncharitable
ungenerous
unprovoked
unscrupulous
vindictive
merciful