post some who looks mad または scary all the time

Kageyama Hiroko from Gilgamesh.
(also known as the countess)

She doesnt just look angry all the time, 95% of the time she is.

Kamui (Gintama) This is his scary look, but he's still cute<3

Kurosaki Ichigo from Bleach
he practically always looks like that.

Megatron in the トランスフォーマー Unicron Trilogy (specifically Energon and Cybertron) constantly has this angry expression on his face (which kinda fits him when あなた think about it), mostly due to the... questionable CGI quality not allowing もっと見る than one facial expression on the トランスフォーマー themselves.

Kakuzu from NARUTO -ナルト- >.< Don't get me wrong, I 愛 him, but I think if I met him, I'd run and him...

Jin & Mugen - Samurai Champloo
I dont think Jin smiled once in the entire series an Mugen always had a pissed off look on his face