Somebody who sucks the life blood out of any and all forms of enjoyment expressed by others.

Sad, bitter, dismal, heartbroken, melancholy, mournful, pessimistic, somber, sorrowful, sorry, wistful, bereaved, blue, cheerless, dejected, despairing, despondent, disconsolate, distressed, doleful, down, down in dumps, down in mouth, downcast, forlorn, gloomy, glum, grief-stricken, grieved, heartsick, heavyhearted, hurting, in doldrums, in grief, in the, dumps, languishing, low, low-spirited, lugubrious, morbid, morose, out of sorts, pensive, sick at heart, troubled, weeping, woebegone