Here is a rather exaustive list of Latin quotes about death with a lot of phrases about sadness and soffering thrown in. They range in their mood from confused annoyance to mild depression. The Latin language is simply best suited for somber and heavy phrases like that. A good number of these quotes is philosophical and contemplative in nature.
A fronte praecipitium a tergo lupi — A precipice in front, wolves behind (between a rock and a hard place)
Abiit nemine salutato — He went away without bidding anyone farewell
Abyssus abyssum invocat — Hell calls hell; one mistep leads to another
Accensa domo proximi, tua quoque periclitatur — When the house of your neighbor is in flames, your own is in danger
Acclinis falsis animus meliora recusat — The mind intent upon false appearances refuses to admit better things (Horace)
Acerrima proximorum odia — The hatred of those most nearly connected is the bitterest of all (Tacit)
Acta est fabula, plaudite! — The play is over, applaud! (Said to have been emperor Augustus' last words)
Ad perniciem solet agi sinceritas — Sinceity is frequently impelled to its own destruction (Phaedrus)
Adeste, si quid mihi restat agendum! — Be at hand, if there is anything more for me to do. (Emperor Severus? last words, according to F. Bacon)
Aegri somnia vana — A sick man's delusive dreams (Horace)
Aequa lege necessitas sortitur insignes et imos — Fate, by an impartial law, is allotted both to the conspicuous and the obscure (Horace)
Aeternum vale — Farewell forever
Bella detesta matribus — Wars, the horror of mothers. (Horace)
Bellum omium contra omnes — Everyman's war against everyman. (Thomas Hobbes)
Bibere venenum in auro — Drink poison from a cup of gold
Bis interimitur qui suis armis perit — He is doubly destroyed who perishes by his own arms. (Syrus)
Brevis ipsa vita est sed malis fit longior — Our life is short but is made longer by misfortunes. (Publilius Syrus)
Cineri gloria sera venit — Fame comes too late to the dead
Consummatum est — It is completed (Christ's last words, John 19:30)
Crudelius est quam mori semper timere mortem — It is more cruel to always fear death than to die. (Seneca)
Curae leves loquuntur ingentes stupent — Slight griefs talk, great ones are speechless. (minor losses can be talked away, profound ones strike us dumb)
Cursum perficio — My journey is over, or I finish my journey
Eheu fugaces labuntur anni — Alas, the fleeting years slip by. (Horace)
Eram quod es, eris quod sum — I was what you are, you will be what I am. (grave inscription)
Est quaedam flere voluptas — There is a certain pleasure in weeping. (Ovid)
Et tu, Brute — And you, Brutus
Extinctus amabitur idem — The same [hated] man will be loved after he's dead. How quickly we forget. (Horace)
Facilis descensus averno — The descent to Avernus (Hell) is easy (Virgil)
Forsan et haec olim meminisse iuvabit — Perhaps someday we will look back upon these things with joy (Virgil)
Forsan miseros meliora sequentur — For those in misery perhaps better things will follow. (Virgil)
Fortuna caeca est — Fortune is blind. (Cicero)
Fortuna vitrea est; tum cum splendet frangitur — Fortune is glass; just when it gleams brightest it shatters (Publilius Syrus).
Fortunae naufragium — A shipwreck of our fortunes (Apuleius)
Graviora manent — Greater dangers await (Virgil)
Hinc illae lacrimae — Hence these tears. (Terence)
In articulo mortis — At the moment of death
Malo mori quam foedari — I would rather die than be dishonored
Memento mori — Remember about death (phrase reputedly whispered to Roman generals during their triumphal victory parades)
Morituri te salutant — Those who are about to die salute you
Mors ultima linea rerum est — Death is everything's final limit. (Horace)
Mors ultima ratio — Death is the final accounting
Mors immatura — Untimely death
Mors vincit omnia — Death conquers everything
Mortem obireTo die, to face death
Mortem Parca affert, opes rursus ac facultates aufert — Fate brings death, and deprives us of wealth and riches
Nascentes morimur — From the moment we are born, we begin to die
Nec mortem effugere quisquam nec amorem potest — No one is able to flee from death or love
Necessaria morte mori — To die a natural death.
Nemo ante mortem beatus — Nobody is blessed before his death.
Nemo nisi mors — Nobody except death (will part us). (Inscription in the wedding ring of the Swedish Queen Katarina Jagellonica)
Non est ad astra mollis e terris via — There is no easy way from the earth to the stars. (Seneca)
Non mortem timemus, sed cogitationem mortis — We do not fear death, but the thought of death. (Seneca)
O curas hominum! O quantum est in rebus inane! — Ah, human cares! Ah, how much futility in the world! (Lucilius)
O quam cito transit gloria mundi! — O how quickly passes the glory of the world!
Omnes vulnerant, ultima necat — All (hours) wound, the last one kills. (a sundial motto)
Omnia mors aequat — Death makes all things equal
Pallida mors — Pale Death. (Horace)
Pars maior lacrimas ridet et intus habet — You smile at your own tears but keep them in your heart. (Martialis)
Plenus annis abiit, plenus honoribus — He is gone from us, full of years and full of honors (Pliny).
Potius mori quam foedari — Rather to die than to be dishonoured (death before dishonour)
Pulvis et umbra sumus — We are dust and shadow. (Horace)
Quod cito acquiritur cito perit — [that] which is quickly acquired [is] quickly lost.
Quod differtur, non aufertur — That which is postponed is not dropped. Inevitable is yet to happen. (Sir Thomas More)
Si post fata venit gloria non propero — If glory comes after death, I'm not in a hurry (if one must die to be recognised, I can wait)
Sic transit gloria mundi — So passes the glory of the world
Solitudinem fecerunt, pacem appelunt — They made a desert and called it peace. (Tacitus)
Tanta stultitia mortalium est — Such is the foolishness of mortals
Tantum nimirum ex publicis malis sentimus, quantum ad privatas res pertinet : nec in iis quicquam acrius quam pecuniae damnum stimulat. — We feel public misfortunes just so far as they affect our private circumstances, and nothing of this nature appeals more directly to us than the loss of money (Livy).
Tempus edax rerum — Time is the devourer of things
Timor mortis conturbat me — The fear of death confounds me
Troia fuit — Troy has been (but it is no more) (Virgil)
Vita sine libris mors est — Life without books is death
Vivere disce, cogita mori — Learn to live; Remember death. (sundial inscription)
Una salus victis nullam sperare salutem — The one safety for the vanquished is to abandon hope of safety (Virgil)