- Astronomical unit
- Astronomy
- Astrophysicist
- Astrophysics
- Astrophysics Academy
- Astrosapling
- Astur
- Aswan Dam
- Asylum (diambiguation)
- Asylum (episode)
- Asylum (novel)
- At Times of Peril
- Ataan
- Ataan Rhukal
- Ataan Rhukal (mirror)
- Atabis
- Atabis system
- Atalia
- Atalia VII
- Atalis
- Atalis IV
- Atalskes Phaser Corporation
- Atalskes phaser III
- Atalskes phaser IV
- Atana Daraan
- Atara
- Atarvi
- Atavachron
- Atawhean
- Atekian apple pie
- Ateleth class
- Atete
- Athan
- Athanares Miasma
- Atheism
- Athena
- Athena Palamas
- Athena Rand
- Athendë
- Athene
- Athene (god)
- Athene Donald
- Athene Donald (Olympic class)
- Athenia Winder
- Athens
- Atherton
- Atheus Fortis
- Athilla Juriss
- Athmin
- Athora Gomorrac
- Athos
- Athos (continent)
- Athos IV
- Athra Dukat
- Athra Dukat (mirror)
- Athus
- Atia
- Atira Meklat
- Atira Sesana
- Atish Khatami
- Atish Khatami (mirror)
- Atlanta
- Atlanta (disambiguation)
- Atlanta Constitution
- Atlanta General Hospital
- Atlantic Ocean
- Atlantic bottlenose dolphin
- Atlantis
- Atlantis (Alpha Centauri)
- Atlantis (NX-05)
- Atlantis (OV-104)
- Atlantis (disambiguation)
- Atlantis Project
- Atlantis Station
- Atlantis class
- Atlas
- Atlas (computer)
- Atlas (disambiguation)
- Atlas VIII
- Atlas class
- Atlas system
- Atlec
- Atlec security vessel
- Atlee Fife
- Atlin Zoological Park
- Atlira class
- Atlirith
- Atlirith (disambiguation)
- Atlirith class
- Atmosphere
- Atmosphere Assault
- Atmosphere replicator
- Atmospheric and Astronomic Council
- Atmospheric generator
- Atnox Depot
- Atom
- Atom War
- Atomic Horrors
- Aton
- Atonement
- Atorec
- Atovra Amerex
- Atoz
- Atrax Messesh
- Atraxi
- Atrea IV
- Atrean
- Atria
- Atrig
- Atrius
- Atrius V
- Atrocitus
- Atropira
- Atrox class
- Atryn
- Attached
- Attack Wing
- Attack cruiser
- Attack fighter
- Attack fighter 6-4
- Attack fighter 6-5
- Attack of the Martians
- Attack on Gravenor
- Attack on Mars
- Attack on Yorktown Station
- Attack raptor
- Attack wing
- Attainder
- Attainment ceremony
- Attanasio Ewan Hodgkin
- Atterace Prees
- Atticus
- Attila the Hun
- Attius
- Attius (Centurion class)
- Attius (Cetratus class)
- Attius (Gladius class)
- Attius (Patronus class)
- Attius (Securis class)
- Attorney General of the United Federation of Planets
- Attrexia
- Attrexian
- Aubar Mrith
- Aubergine stew
- Aubin Tabor
- Aubrey (transport)
- Aubrey Townsend
- Auceo (Caeliar)
- Auceo (disambiguation)
- Auckland
- Audacious
- Audible.de
- Audiobook
- Audit's Spoils
- Auditor general
- Auditory filter
- Audre Lorde
- Audrey
- Audrey (Lady)
- Audrey Willa
- Audrid Dax
- Audubon Park
- Augav
- Augenthaler
- Auger
- Auger (disambiguation)
- Augment
- Augment Alliance
- Augment Crisis
- Augments faction
- Augments faction (Kelvin timeline)
- Augur
- August
- August Macke
- Augusta Savage
- Augustin Padilla
- Augustus
- Augustus Betances
- Augustus Bradford
- Augustus Gamma
- Augustus Prime
- Auk-rex
- Aulac
- Aulacri
- Aulep
- Aulia (disambiguation)
- Auloc Amexar
- Aulus
- Aumoide Pore
- Aunithox
- Aur (General)
- Aura Daren
- Auraciem
- Aurelan
- Aurelan Kirk
- Aurelan Kirk (Kelvin timeline)
- Aurelia
- Aurelia (composer)
- Aurelia (disambiguation)
- Aurelia III
- Aurelia IV
- Aurelia Prime
- Aurelian
- Aurelie
- Aurelius
- Aurelius (disambiguation)
- Auriga
- Auriga constellation
- Aurilla Lorexen
- Aurobindo Korrapati
- Auroc Amexar
- Auron
- Auron Tharaxes
- Aurora
- Aurora (Human)
- Aurora (NC-17740)
- Aurora borealis
- Aurora class
- Aurore De Blois
- Aurowaqqa
- Aurulent
- Austin
- Austin (artist)
- Austin (disambiguation)
- Austin Braddock
- Austin Chang
- Australia
- Australia (disambiguation)
- Australian Outback
- Austria
- Ausuch
- Autarch of the Tzenkethi Coalition
- Author's annotations
- Author, Author
- Authorization code
- Autism
- Autobreather
- Autochef
- Autoclave
- Autograph
- Automated Command Unit One
- Automated Personnel Unit
- Automated janitorial system
- Automated worker
- Automatic bridge defense system
- Automatic pistol
- Automobile
- Autopilot
- Autopsy
- Autosurgeon
- Autotuner
- Autry
- Auva
- Auvarak Messesh
- Auvellex Lorexen
- Auxiliary control
- Auxiliary medical probe
- Av'tel
- Avaihh lli vastam
- Available Light
- Avalon
- Avalon (CM-5)
- Avalon (disambiguation)
- Avalon Rising
- Avan
- Avandar
- Avara
- Avarald
- Avaranthi sh'Rothress
- Avaril
- Avastam
- Avatar
- Avatar, Book One
- Avatar, Book Two
- Avatar (disambiguation)
- Avatar (robot)
- Avatrunei
- Avek
- Avel
- Avelik
- Avell
- Avelos
- Avem-4
- Aven Meru
- Avenal
- Avenal Station
- Avenal VII
- Avenger
- Avenger (NX-09)
- Avenger (disambiguation)
- Avenger class (battlecruiser)
- Avenger class (scout)
- Aventeer Vokar
- Aventine class
- Avenue Renak
- Avenue of Processions
- Avenue of the Emissary
- Averell Harriman
- Averill Stanton
- Aversion
- Avery
- Avery (disambiguation)
- Avery Bessent (23rd century)
- Avery Bessent (24th century)
- Avery Brooks
- Avery I
- Avery III
- Avery system
- Aves class
- Avian
- Avianoid
- Avinall VII
- Avior
- Avior VIII
- Aviskie
- Avogadro Center
- Avomora
- Avoth
- Avox tai-Sannid
- Avrak
- Avril Station
- Avro
- Avro Lancaster
- Avro Wraor
- Avul Vayishra
- Awakening
- Awakening (STO)
- Away Missions
- Away Team
- Away team
- Awnedre
- Awrenn Reshtarc
- Axa
- Axael Krinn
- Axanar
- Axanar (disambiguation)
- Axanar Peace Mission
- Axanar War
- Axanarri
- Axe
- Axel
- Axel (disambiguation)
- Axel Carruthers
- Axelot
- Axelot II