Mon Calamari cruiser
In the Star Wars fictional universe Mon Calamari Star Cruisers are the main cruisers in the Rebel/New Republic fleet for a significant portion of the Galactic Civil War. They were originally built for civilian purposes, but were converted to military starships when the Empire conquered the Mon Calamari. While they are exceedingly durable starships, they are also notoriously difficult to repair, in part because of their individualized design. Rebellion-era Mon Calamari ships have very powerful shield generators, in part because their civilian-spec hull structure is somewhat weaker than a true military starship.
Mon Calamari star cruisers come in several general shapes - a wingless shape resembling a large pickle with space drive engines, a winged type known to fanon as the Liberty-class, and a design twice as long as a standard Imperial Star Destroyer and nearly as powerful as an Executor-class Super Star Destroyer, exemplified by NRS Home One, which was Admiral Ackbar's flagship at the Battle of Endor. There were two variants of the "wingless" design at Endor, one some 1200 meters long and another resembling a Liberty but with the wings deleted.
By the time of the New Republic, the Mon Calmari had begun to produce military-optimized designs that were no longer modified civilian designs. The hallmark of the design was typically very strong shielding with a respectable battery of turbolasers and ion cannon. Fighters were usually -- but not always -- carried onboard. The individualization that marked the Rebellion-era designs all but disappeared in an effort to simplify the New Republic's logistics.
The designation of these ships is somewhat curious. The term "MC80" or "MC90" may actually refer to some tonnage class. In the case of the MC90, two ships of that class (NRS Defiance and NRS Galactic Voyager) had wildly differing designs. Proper class names did not appear until the arrival of the Mediator.
Some early source material referred to the ships at Endor as frigates, including the flagship Home One. This is nonsensical; most of the heavy Mon Calamarian ships in the battle were similar in length to Imperial Star Destroyers (if not longer) and often with much greater internal volume. Most orders of battles in Star Wars have frigates as being ships around the size of the diminutive Nebulon-B. One possibility is that the Rebellion called cruisers designed on destroyer hulls "frigates," much like the United States Navy did at one time; the small ships like the Nebulon-B would be called escort frigates to differentiate them.
A brief description of some common Mon Calamari warships is listed below. This list is not exhaustive; some cruisers have been described but never named:
MC80
A design 1200 meters in length and commonly encountered during the time of the Rebellion. These were almost all converted merchant liners and somewhat inferior in performance to their Imperial counterparts, the Imperial Star Destroyer. The control systems were optimized towards Mon Calamarian biology which caused some problems with the diverse makeup of the Rebel Alliance. In addition, each ship in this type was subtly different: most Mon Calamarian civilian liners are independently customized. While these vessels were robustly constructed, they were difficult to repair due to their customizations.
MC80A
The MC80A was a production-streamlined version of the MC80 that was deployed en masse by the nascent New Republic. While it was still optimized for the Mon Calamari, the ship design was standardized.
MC80B
The MC80B was an interim design partially based on the MC80A lineage. It possessed unusually strong shields and armor which allowed it to fight on more than even terms with most enemy ships (including ISDs). Three flights were launched, with zero, four or eight fighter squadrons, respectively. General Han Solo flew his flag from one of these cruisers.
MC90
The MC90 was the first heavy combatant designed from the ground up for the New Republic. It was an exceptionally powerful design (and also extremely expensive). It was primarily relegated to flagship duties due to its extensive command and control facilities, which were also reconfigurable for other species. This design was capable of close combat with an Executor-class Star Dreadnought (albeit without damage to either ship).
Home One
Home One was Admiral Ackbar's flagship during the Battle of Endor. It is over twice the length of an Imperial Star Destroyer and carries 120 starfighters. Her shields are powerful enough to withstand close combat with an Executor-class Star Dreadnought; however, her firepower is somewhat lacking. The hanger layout is also non-optimal with large openings on her port and starboard surfaces. Official literature places this ship with the paltry armament of 29 turbolaser batteries and 36 ion cannon, but these numbers could be transpositions.
Home One may be a callsign rather than the actual ship name. There has been some speculation as to whether Ackbar's flagship was named Independence, but the evidence suggest that Independence and Home One are not the same ships.
Liberty
The Liberty has the dubious distinction of being the first ship destroyed by the Death Star II. This type was some 1500 meters long and had a sort of delta-winged design for greater surface area. It presumably was more powerful than other Rebellion-era ships such as the MC80 series. Unlike most Rebellion-era designs, her hangers appeared to have been buried near wingroots. While not the best design as far as fighter operations are concerned, this would provide excellent protection.
Anonymous Wingless
Similar to the Liberty but without the large delta wings. It is commonly mistaken for the MC80 series.
Mediator-class Star Battlecruiser
A much larger and more powerful cruiser that was introduced into the New Republic Defense Force shortly before the Yuuzhan Vong invasion. Its designation as a battlecruiser implies that she is far stronger than any Mon Calamarian cruiser than has gone before her.
Viscount-class Star Battleship
An enormous cruiser designed shortly before the Yuuzhan Vong invasion. Few operational examples existed and their production run may have been halted or delayed in favor of a greater number of lesser warships. In the literature the ship is described as a "Star Defender" which is rather odd. As the Viscount is over twice the size of the Mediator, she may well compare with ships such as the Executor-class Star Dreadnought.