If you're struggling in life, these ones first
Kevin Braddock – Everything Begins With Asking For Help
John Powell – Why Am I Afraid To Tell You Who I Am?
Marcus Aurelius – Meditations
Bessel van der Kolk – The Body Keeps The Score
Vincent Deary – How We Are
Darian Leader – The New Black 
Vicktor D. Frankl – Man's Search For Meaning
Anthony De Mello – Awareness 
Alan Watts – The Wisdom Of Insecurity: A Message For The Age Of Anxiety 

Depression
Edward Bullmore – The Inflamed Mind 
Dr Tim Cantopher – Depressive Illness, The Curse of the Strong 
William Styron – Darkness Visible 

Mind & Body
Gabor Maté – When The Body Says No
Haruki Murakami – What I Talk About When I Talk About Running
Olivia Laing – Everybody

Understanding Psychotherapy
Irvin D. Yalom – Love’s Executioner
Frank Tallis – The Act Of Living
Susie Orbach – The Impossibility Of Sex
Carl Rogers – On Becoming A Person
Stephen Grosz – The Examined Life
Alice Miller – The Drama Of Being A Child
Adam Phillips – Going Sane
Esther Perel – Mating In Captivity
Darian Leader – What Is Madness?

Philosophy, Stoic & Otherwise
Seneca – On The Shortness Of Life
Nassim Nicholas Taleb – Antifragile + Skin In The Game
Dan Millman – The Way Of the Peaceful Warrior
Sarah Bakewell - At The Existentialist Cafe
John N. Gray – Straw Dogs
John N. Gray – Feline Philosophy

Mindfulness, Zen, Tao & Spirituality 
Lao-Tzu – Tao Te Ching
Deng Ming-Dao – 365 Tao: Daily Meditations 
Thich Nhat Hanh – Peace Is Every Step 
Alan Watts – Become What You Are
Alan Watts – The Way Of Zen
Alan Watts – What Is Tao?
William James – The Varieties Of Religious Experience
Eckhard Tolle – The Power Of Now

Addiction & Recovery
Gabor Maté – In The Realm of Hungry Ghosts
Alcoholics Anonymous – Living Sober
Alcoholics Anonymous – Alcoholics Anonymous
James Frey – Million Little Pieces + My Friend Leonard
Amy Liptrot – The Outrun
Denis Johnson – Jesus’ Son
Hans Fallada – The Drinker

Psychoanalysis
Sigmund Freud – The Interpretation Of Dreams
Sigmund Freud – Mourning & Melancholia
Sigmund Freud – Papers On Technique
Sigmund Freud – Beyond The Pleasure Principle
Lavinia Gomez – Introduction to Object Relations
Bruce Fink – Lacan on Love
DW Winnicott – Home Is Where We Start From
Nina Coltart – Slouching Towards Bethlehem
Michael Kahn – Basic Freud
RD Laing – The Divided Self
Jessica Benjamin – The Bonds Of Love

Being A Man
Robert A. Johnson – He: Understanding Maculine Psychology
Robert A. Johnson – The Fisher King & The Handless Maiden
Robert Bly – Iron John
Gillette & Moore – King Warrior Magician Lover: Rediscovering The Archetypes of The Mature Masculine

PS: yes, I’ve read all of these. Sometimes more than once - Kevin