“Till death us do part”
is a quotation from The Book of Common Prayer in the Solemnization of Matrimony or Marriage Service.   It has been used as the title of a British TV sitcom.

As dead as a doornail
is an old expression.  Nowadays there are more and more PVC doors which do not have nails.  A doornail has never been alive…

…unlike a dodo, which is an extinct bird, giving rise to the simile as dead as a dodo.

Photo credit Wikipedia http://en.wikipedia.org/wiki/File:DodoMansur.jpg

I wouldn’t be seen dead in that
is a statement about taste in clothes.  Do people really worry about what they will be wearing at the moment of their death, or what they will be laid out in afterwards?

Dead men’s shoes is an expression about career progression.  If a company is not expanding and everyone has long employment contracts, the only hope of promotion is if someone dies.

Over my dead body means I will do everything I can to prevent that.

I’m dead beat or tired out.

 When I’m dead and gone…

…my influence will be less.

“Gone, but not forgotten”
could refer to the dead, or just someone who has moved away as could long gone.

A dying art is a description of something , which used to be commonplace and is now a specialist job.  Thatching is an example.

Curtains is a euphemism for death.  Perhaps it refers to the end of a play or to the curtains which are drawn behind the coffin (casket) at a crematorium.

That’s your funeral is a remark which tells the previous speaker that the present one has no sympathy for their problems.

She’d be late for her own funeral is a play on words.  It is usually an impatient remark about a habitually tardy person, but anyone who is dead is referred to as late.

Someone walked over my grave.
This is what people say when they shiver unexpectedly on a warm day.

Enough to make him turn in his grave refers to a situation which the deceased would have deplored.

Pushing up daisies refers to being buried and providing nutrition for plants.

There is an old joke about Beethoven.
Q.  What is Beethoven doing in his grave?

A.  Decomposing.

Hold on for grim death is often used figuratively –   perhaps it comes from mountaineering.

They’re dropping like flies
is often said when there are a lot of deaths in a short space of time.

How are the mighty fallen is from the Bible.  It refers to King Saul and his son, Jonathan.  The story can be found in 2 Samuel Chapter 1.

Jesus said (John Chapter 11 verse 25  NIV), “I am the resurrection and the life.  He who believes in me will live, even though he dies; and whoever lives and believes in me will never die.  Do you believe this?”

If I were at death’s door I’d not be writing the post to end all posts in response to Daily Prompt: Last words