The images below are all exactly to scale, each pixel equals one hundred meters a side. Internet Explorer users may Click and Drag the starships to compare them as you like. At the bottom of the image are some contemporary vehicles and buildings for reference. Have fun!

V'Ger from Star Trek: The Motion Picture, 98 km long

SHIP NAME/TYPE: V'Ger (Voyager VI)
LENGTH: Approximately 98 km.
BUILDER/COMMENTS: Originally built by humans and launched near the end of the 20th century for peacful reconnaisance purposes, the Voyager VI probe was intercepted by an evidently technologically advanced race who augmented the probe and sent it back to Earth under a new internal conciousness, resulting in a near cataclysm.
SOURCE: Star Trek, the Motion Picture (Film, 1982 Paramount Pictures), Drawn by Jeff Russell

Whale Probe from Star Trek IV, 74 km long

SHIP NAME/TYPE: Whale Probe
LENGTH: Approximately 74 km. There are numerous conflicting sources for the length of the Whale Probe, but extrapolation from the film has led me to accept this length as being the most likely.
BUILDER/COMMENTS: Unknown, although the device was able to communicate with humpback whales.
SOURCE: Star Trek IV, (Film, Paramount Pictures)

Marduk Base from Macross II, 50 km diameter

SHIP NAME/TYPE: Marduk Mothership
DIAMETER: Approximately 50 km. This is the stated length of the RPG version, although the movie version seems to be much larger. Further investigation is needed.
BUILDER/COMMENTS: Marduk, the creators of the Zentraedi.
SOURCE: Macross II, (Animated Film), Drawn by Jeff Russell

Island Three

SHIP NAME/TYPE: Island Three space colony
LENGTH: Main habitat cylinder approximately 32km, diameter 6.4km
BUILDER/COMMENTS: A. Twu: "Island Three is a scaled up version of Island Two. It has the same proportions, but has a diameter of 6.4 km and a population of 10 million. The larger diameter means the atmosphere inside is thick enough to create a blue sky effect. It is also known as the O'Neill Cylinder or the 'sunflower'. Island Three type colonies are depicted in the anime Mobile Suit Gundam series."
SOURCE: Image created by A. Twu

Rama, 50km long

SHIP NAME/TYPE: Rama
LENGTH: 50 km long, 20 km in diameter.
BUILDER/COMMENTS: Large habitat ship
SOURCE: Rendezvous with Rama, Arthur C. Clark, Drawn by Jeff Russell

Vorlon Planet Killer, approximately 45km long

SHIP NAME/TYPE: Vorlon Planet Killer
LENGTH: Approximately 45 km. There are numerous conflicting sources for the length of the Vorlon Planet Killer, but extrapolation from the show has led me to accept this length as being the most likely.
BUILDER/COMMENTS: The Vorlon
SOURCE: Babylon 5, (Television Series)

Phobos, moon of Mars, 27km long at longest axis

SHIP NAME/TYPE: Phobos
DIAMETER: 27 km x 23 km x 20 km
BUILDER/COMMENTS: Moon of Mars
SOURCE: Discovered in 1877, August 12 by Asaph Hall; photographed by 'Mariner 9' in 1971, 'Viking 1' in 1977, and the Russian 'Phobos' probe in 1988.

City Destroyer from ID4, 24km diameter

SHIP NAME/TYPE: ID4 City Destroyer
DIAMETER: 24 km across, stated in the film.
BUILDER/COMMENTS: ID4 Aliens. Please see notes
SOURCE: Independence Day (Film), Drawn by Jeff Russell

Cloud City, 16km diameter

SHIP NAME/TYPE: Cloud City
LENGTH: 16 km.
BUILDER/COMMENTS: Bespin Mining Colony
SOURCE: Star Wars Episode V, the Empire Strikes Back (Film), Drawn by Jeff Russell

Super Star Destroyer from Star Wars, 12.8km long

SHIP NAME/TYPE: Executor/ Super Star Destroyer
LENGTH: 19km (Official), Please see http://www.theforce.net/swtc/ssd.html for an alternate length and discussion.
BUILDER/COMMENTS: The Empire under Darth Sidious (human). Darth Vader's command ship.
SOURCE: Star Wars Episode V and VI, the Empire Strikes Back, and the Return of the Jedi, (Film), originally drawn by Chad Wilson

Lexx, 10km long

SHIP NAME/TYPE: LEXX
LENGTH: 10 km. From original Blueprints used in the design of the ship.
BUILDER/COMMENTS: The Empire under His Devine Shadow (human). This vessel is a wepon capable of destroying an entire Earth Size planet.
SOURCE: LEXX (TV series)

Babylon 5 Space Station, 8454.1m long

SHIP NAME/TYPE: BABYLON 5/ Deep Space Station
LENGTH: 8,454.1 m, from http://www.b5tech.com/babylonproject/babylon5station/babylon5station.html
BUILDER/COMMENTS: Human. "Babylon 5 is a 8,454.1* meter (five-mile) long, 840 meter diameter, 9.1 billion ton O'Neil class space station, located at a pivotal main jump gate in the Epsilon system."

SOURCE: Babylon 5 (TV series)

Star Trek Star Base

Macross I & II capital ships

SHIP NAME/TYPE: MACROSS Starships
LENGTH: Various
BUILDER/COMMENTS: Various
SOURCE: Macross (Animated film)

Crysis Alien Ship

SHIP NAME/TYPE: Alien Ship from 'Crysis' video Game
LENGTH: 3475m
BUILDER/COMMENTS: http://www.ea.com/crysis/index.jsp
SOURCE: 'Crysis' video Game

Babylon 5 capital ships

SHIP NAME/TYPE: BABYLON 5 Starships
LENGTH: Various
BUILDER/COMMENTS: Various
SOURCE: Babylon 5 (TV series)

Death Star II from Star Wars, episode VI, 160km diameter (official size)

SHIP NAME/TYPE: Death Star II/ Mobile Command Base
DIAMETER: 160km (official size, see http://www.theforce.net/swtc/ds/ for an alternate size theory and discussion.)
BUILDER/COMMENTS: The Empire under Darth Sidious (human). Incorporated into the base is a laser-type weapon capable of destroying an entire Earth sized planet.
SOURCE: Star Wars, Episode VI (Film)