The Horizon class was a type of early Earth/Federation exploration ship. It had limited weapons and defences, with a maximum speed of warp 3. (TOS reference: Spaceflight Chronology)

Starship classes of Earth
Arrow • Assist • Cavalry • Christopher • Cosmos • DY-100 • DY-500 • DY-700 • DY-1100-class • Daedalus • Discovery • Doppler (scout) • Edison • Galliant • Hopkins • Horizon • Intrepid (Earth) • J (freighter) • Long • Marshall • Mercury • Messier • Minuteman • NX • Poseidon • Strider • Vanguard (starship) • Verne • Y (freighter) • Yorktown • Zeus

Starship classes of the United Federation of Planets
By name	Aakenn • Achernar • Achilles • Advance • Aegian • Aeolus • Aerie • Akira • Akula (destroyer) • Akula (frigate) • Alaska • Ambassador • Andes • Andromeda • Andor • Antares • Anton • Apache • Apollo • Archer • Ariel • Ascendant • Avenger • Babcock • Bader • Baker • Baton Rouge • Bode • Bolarus • Bonaventure • Bonhomme Richard • Bradbury • Brenton • Canada • Canopus • Capella • Centaur • Centaurus • Cerberus • Challenger (deep space explorer) • Challenger • Chandley • Charger • Chariot • Chesapeake • Cheyenne • Chimera • Christopher • Cle Dan • Cochise • Cochrane • Constellation • Constitution • Continent • Copernicus • Cygnus • Daedalus • Danube • Decatur • Decker • Defender • Defiant • Deneva • Derf • Dollond • Doppler • Dreadnought • Drexler • Durrett • Eagle • Edward • El Dorado • Enterprise (23rd century) • Enterprise (alternate future) • Epoch • Epsilon • Erewon • Excalibur • Excelsior • Federation • Fenlon • Fermi • Fiji • Freedom • Frontier • Gagarin • Galaxy • Galen • Geneva • Genser • Graceful • Grayson • Griffon • Hale • Hardin • Hephaestus • Hermes (scout) • Hermes (fast cruiser) • Heston • Hogan • Hokule'a • Horizon • Huron • Icarus • Incursion • Indomitable • Intrepid • Iowa • Istanbul • Iwo Jima • Class J • Karekh • Keith • Keppler • Kethkin • Kiev • K'Kmarak • Kolm-An • Korolev • Larson • Lauro • Laweya • Legacy • Lenthal • Lexington • Liberty • Loki • Loknar • London (troop transport) • Luna • Makin • Mann • Marklin • Marshall • M'Benga • Mediterranean • Merced • Mercury • Merian • Messier • Midway • Miranda • Mission • Missouri • Mockingbird • MoKal • Monoceros • Moscow • Mulciber • Nebula • Nelson • New Orleans • Newport • Niagara • Noble • Nomad • Northampton • Norway • Nova • Oberon • Oberth • Odin • Odysseus • Odyssey • Okinawa • Olympic • Oppenheimer • Orion • Osaka • Overfield • Paladin (destroyer) • Paladin (24th century) • Philadelphia • Phoenix • Pinnacle • Piper • Polarity • Pollux • Portsmith • Premonition • Prometheus • Proxima • Ptolemy • Pyrenees • Rakota • Ranger (cruiser) • Ranger (scout) • Reliant • Remora • Renaissance • Rickenbacker • Rigel • Rochester • Royal Sovereign • Saber • Sagan • Saladin • Samson • Santa Fe • Sawyer • Scorpio • Scylla • Sequoia • Shi'Kahr • Sierra • Siva • Solar • Sovereign • Soyuz • Springfield • Steamrunner • Surak • Sydney • Venture • Tangent • Theophrastus • Thomas Paine • Thucydides • Thufir • Ticonderoga • Tikopai • Tritium • Typhon • Ukora • Ulysses • Ural • Utah • Vesta • Vigilant (scout) • Vigilant (tactical escort) • Voyager • Wambundu • Wilkerson • Wei-Fa • Wellington • Wells • Yamato • Yorkshire • Zodiac • unnamed
By type	Federation cargo ship • Federation colony ship • Federation construction ship • Federation galaxy ship • Federation light cruiser (Intrepid-variant) • Federation mining freighter • Federation repair ship

Ships of the Spaceflight Chronology
Advance-class • Baton Rouge-class • Bode-class • Constitution-class • Declaration-class • Eagle-class • Hale-class • Horizon-class • Mann-class • Marshall-class • Portsmith-class • Rickenbacker-class • Sawyer-class • Stellarford-class • Tritium-class