Well , here is the list that in my opinion , are the best horror games for xbox 360 until now :

1-. Condemed : criminal origins

2-. F.E.A.R

3-. Silent Hill 2 Restless dreams

4-. Silent Hill 4 The room

5-. Dead Space

6-. F.E.A.R 2

7-. Dead Space 2

8-. Silent Hill Homecoming

9-. Bioshock

10-.Condemned 2 Bloodshot

That the best horror games in my opinion until now , maybe some are not in the place they have , so give me your opinion about it :)