_when guest stars come a-calling : muhammad ali on `` touched by an angel '' -lrb- may 9 , cbs -rrb- ; jason alexander as the voice of evil human resources director catbert on `` dilbert '' -lrb- monday , upn -rrb- ; coolio warming up for his new series on `` malcolm & eddie '' -lrb- tuesday , upn -rrb- ; kathy bates as an alien hunter on `` 3rd rock from the sun '' -lrb- tuesday , nbc -rrb- ; nfler rodney peete with real-life wife holly robinson peete on `` for your love '' -lrb- may 13 , wb -rrb- ; billy dee williams on `` promised land '' -lrb- may 20 , cbs -rrb- ; william shatner as `` the big giant head '' on the one-hour season finale of `` 3rd rock from the sun '' -lrb- may 25 , nbc -rrb- .