'grim death' is correct and usable in written English.
It can be used to refer to death in a poetic or dramatic way. For example, "The Grim Reaper was an ever-present reminder of grim death."
"I was hanging on for grim death.
They turn niggling knocks into something closer to grim death.
Do you want to act out its ghastly denouement with its last, grim death laugh?
Patients with idiopathic pulmonary fibrosis face a grim death, usually two to five years after diagnosis.
Peacock played a spaceman, dying a grim death inside his pressure suit.
You'd write poignant diary entries and then, in all likelihood, die a grim death in the snow.
With the eyes of the country on the parliament, on 48 hours of grim, death-match politics, both leaders framed their own tests of character.
But why? Apart from Her Majesty, the most enduring blockbusters of Christmas telly are the soaps, despite their grim death-and-divorce storylines.
Private Montgomery was concerned that the grim deaths of the four had already become national news back home.
Garner turns what she calls the "shit-detector" of a woman of her years on the mysteries behind these grim deaths.
As the fifth series of Game of Thrones reaches its conclusion with an episode that will apparently "break the internet" (according to spoiler-filled links like this), viewers are increasingly split as to whether this show is a dark and serious examination of the true cost of war, or a gruesome entertainment with an over-reliance on shocking twists and grim deaths.
