Translation of "Grin" in Japanese

He gave his sudden, goblin like grin.

彼はいつものように突然不気味な笑みを浮かべた。

That person has had an odd grin on his face for a while. What do you suppose is behind it?

さっきからあの人一人でにやにやして。怪しい。

You could tell by the ear-to-ear grin that came to his face that he really had something to smile about.

喜色満面の笑みを浮かべているけど、彼、よっぽど嬉しいことがあったんだろうな。