http://www.mangago.me/read-manga/bastard_hwang_youngchan/
^read on line webtoons. its totally free ;>
(*⁰▿⁰*)
http://www.mangago.me/read-manga/goth/
http://www.mangago.me/read-manga/kami_no_kodomo/
http://www.mangago.me/read-manga/death_note/
http://www.mangago.me/read-manga/madk/
http://www.mangago.me/read-manga/aku_no_kyouten/
http://www.mangago.me/read-manga/the_moon_is_beautiful_tonight_but_first_die/
http://www.mangago.me/read-manga/shin_ai_naru_boku_e_satsui_wo_komete/
http://www.mangago.me/read-manga/an_uncomfortable_truth/
Male MC that's a psychopath or a serial killer or whatever's similar.
Or basically he's not right in the head.
Brutal and PIGPEN are some that I've read. I've also read the one with the gross pumpkin head (even though it's a female mc).