Broadly speaking, Dragonstar has the same classes as Dungeons and Dragons (and Pathfinder). That said, the setting does demand some changes to classes and allows others some new opportunities.
Modern and futuristic technology is of great value to bards. Many bardic abilities have ranges based on vision and hearing, and so it is common for groups that include bards to wear helmets with HUDs and radios that allow their Bard ally to stay relatively safe and still confer their bonuses. Bardic abilities do still need line of effect, however, so Bards can't just stay on the ship and perform tiny desk concerts for their buddies who are risking life and limb planetside.
Modern entertainment culture means that Bards can become quite famous and well-known, allowing them to act as the party face even more reliably.
(Barbarian from PHB, PF, Tome)
Though there are some bersekers who do come from the stereotypical First Nations/Nordic/Paleolithic tribe background that the Barbarian class is often written assuming, the typical berserker of Dragonstar is just a warrior who channels their anger to improve their combat ability. Certainly, there are cultures that have strong warrior traditions that have some berserkers, but they are not paleolithic, generally speaking. Klingon berserkers are a totally iconic thing, but the Klingons aren't running around with ships cobbled together with Flintstonian Schizotech.
Orcs are renowned for producing such berserking warriors, but there is a recognized tendency for dragonblooded species to produce berserkers as well, who are able to harness the strength and fury of their draconic ancestors in combat.
Berserkers in Dragonstar are greatly aided by the various high tech and magically augmented weapons and armors.
The universe of Dragonstar includes countless worlds with truly enormous numbers of pantheons. Scholars have noticed common themes in these pantheons and posited a unified pantheon of archetypes that has become the de facto Dragon Empire pantheon. These archetypes are often referred to by a simple title, such as The Mother, or The Destroyer, but if you ask anyone who is in any position of power in the Dragon Empire about them, they will likely use the names of the gods in the Draconic pantheon which match a given archetype.
In effect, virtually any combination of domains is possible, save for opposed alignments, as there is ostensibly some god worshipped on some planet that possesses any given combination, even, say, Undeath and Community.
Domains from Spell Compendium and Pathfinder are equally fair game, and I'm open to working with players to develop custom domains if desired.
Druids and Rangers Edit
Druids in Dragonstar tend to be more open minded than those in other settings, if in no other way than being more accepting of aberrations. In Dragonstar, aberrations are less inimical to non-aberration life and more just strange life from specific planets. Druids may join up on ships out of curiosity about life elsewhere, or an interest in protecting that life from less than conscientious exploration crews.
Rangers are much the same, though they are less likely to leave a single planet. When they do, they are often more bounty-hunting and less nature oriented.
Mechrids are similar in overall ability to Druids, but instead of interacting with animals, they form a connection with technology. Their major abilities are all enabled through a cybermesh and nanite colony, and instead of an animal companion, mechrids have mechanoid companions which they can customize and upgrade given time and equipment.
Martial Technicians Edit
(Brawlers, Tome Fighters and Monks, Manuever users)
There are always those who chose to devote their time and focus to purely martial techniques, aided more by equipment or knowledge than magic or supernatural ability. They may be soldiers, hitmen, bounty hunters, or other who make a living through violence.
The truly cosmopolitan nature of the Dragonstar setting means there is a great variety of martial styles ability for study.
Sorcerers, Warlocks, Witches, Wizards Edit
Sorcerers are prized in the Dragon Empire. They are assumed to have a drop of dragon blood in them so long as they don't make it known they do not. Thus, even if a sorcerer comes by their power through outsider or fae lineage, so long as it's not obvious, they benefit just as much as other sorcerers in the Dragon Empire.
Warlocks (and Dragonfire Adepts) that gain their power from dragons similarly have a leg up on prestige in the Empire, but without an obvious sign, it is assumed that warlocks gain their power from outsiders, usually fiends, and fiends are not trusted in the Empire. the fiendish dragon varieties are even more reviled, though its a revilement tinged with begrudging respect as they are still dragons.
Witches are typically seen as minor hedge casters, whether they are or not. Witches with more than modest power are usually assumed to be one of the other caster types.
Wizards are an interesting case. They are seen as uppity thieves, but seldom does anyone voice that opinion, due to the fact that a wizard is often quite powerful, and if the one in front of you isn't, you probably know one that is, and would take offense to your slandering of wizards. Not only that, but dragons, innate arcanists though they may be, often study magic themselves.