I'll have a go:
1). Human male. Marine. Lieutenant Fresh out of the Academy. Engineer. Think Jenkins, with a dash of Kaidan and James Vega thrown in. This is his first mission, but he's got a Mindoir type background to drive him, so he's not as fresh faced as he might seem on the surface, but he has that Alenko romantic outlook on space and the future from ME1. Bisexual Romance.
2). Human Female. Marine. Mid-thirties. Combat Veteran with an archive of "No S***" stories. Soldier. Basically, a female Zaeed with *less* facial scaring. Collects My Little Ponies dolls. Likes pink, flowers, and anything girly. Anytime you approach her for conversation, there's a 50/50 chance she'll be field stripping a gun that could hole a tank, or reading some sappy romance novel with a box of tissues. Bisexual Romance.
3). Turian Female. Former Scout/Recon. Mouthy. Cool. Death Incarnate with a Sniper Rifle. Infiltrator. Basically, a female version of Garrus, crossed with Black Widow from Captain America: The Winter Soldier. Bisexual Romance.
4). Turian Male. Biotic Cabalist. Vanguard. Former Spectre who said to hell with it and walked away. Older, grizzled. Visible Scars, a cybernetic arm, a cybernetic eye, and a mandible that's either missing the front half, or has it visibly replaced with cybernetics. This guy has seen the Elephant, and got trampled, repeatedly. Think, a less indoctrinated Saren, who isn't a racist bigot, but who's seen every rotten thing the galaxy has to offer. Bitter and disaffected with the Hierarchy. Bisexual Romance.
5). Female Krogan Warlord. 1600 Hundred years old. Biotic. Sentinel. Thoughtful. Intelligent. Fantastic sense of human. A fondness for poetry, and a keen interest in history and spirituality. Fought along side Shiagur in the Krogan Rebellions. A mix of Samara, Bakara and Ashley Williams. Non-Romance.
6). Asari Commando. Adapt. Matriarch. She's nearly 1200 years old, and she's seen and done it all. She's raised daughters, fought wars, loved, lost, grieved and got better. She also watched her daughters, grand daughters, and even great grand daughters fed into the grinder of the Reaper War, and doesn't much like to think about how many of them didn't come back. A mix of Aethyta and Purple Fem!Hawke. Female only Romance.
7). Drell Male. Sentinel. Not dying of Kepral's Syndrome. Trained spy, assassin and saboteur. Resents the Hanar, and considers the compact the de facto enslavement of his people. Has a completely different philosophical outlook than Thane, and a different religion. Male only Romance.
8). Salarian Female. Soldier. Former STG. 20 years old. Completely disaffected with Salarian Culture. Think absolutely hates the practice of deliberately keeping down the numbers of Salarian females. Effectively told her family to stick it right up their Chloaca when they wanted her to spend her life as a brood mare. Went on to serve with distinction in the STG, before the political pull of her family lead her to walk away from Salarian culture altogether. Non-Romance.
9). Volus Female. Vanguard. Marine Major in the Volus Defense Force. Absolutely having none of your BS. Can, and will kick your posterior right up around your ears. She's an absolutely brilliant business woman. Fantastically rich due to how well she manages her investments. But finds it terribly boring and would most rather be out on the front lines cutting a bloody swath though pirates, slavers, geth, Reapers, or anything else she's given permission to kill. She's a Krogan Battle Master who got reincarnated as a Volus, but kept the blood rage and the love of Mayhem. Wields a customized, double barrel, fully automatic Claymore that can not be unequipped. It's named Tethas'Var. Likes to tell Stories. Non-Romance.
Pilot). Human Female. Cybernetic Arm and leg and facial scaring on the right side. Former fighter pilot. She got jumped by pirates while flying CAP for a human carrier. Managed to cover the carrier long enough for them to scramble fighters, but took one to many hits. Managed to land her bird, but got maimed in a cockpit fire before the deck crew could cut her out of the wreck. Transferred to ship helms because military regs prevent pilots from flying fighters if they have cybernetic limbs. Cheerful, good sense of humor. Incredibly Smart. Female Only Romance.
Executive Officer). Human Male. A bit on the young side. Smart, fast thinking. A bit cynical, and defensive because of his age. Really good at his job to have reached his rank so young. Career navy. Grew up on space ships, and thinks planets are completely gross germ factories. Female Only Romance.
Doctor). Human Female. Attractive. Sarcastic. Thinks you're an idiot for letting yourself get shot at all the time. Morrigan in a medical uniform. Male Only Romance.
Ship's Psychiatrist). Male. Old as dirt. Facial scars that make Hackett and Zaeed wince. Former N7 operative. Retired after getting caught in an explosion, went to medical school, then specialized in psychiatric care, with a focus on combat related PTSD. Non-Romance
Comm Specialist). Human Male. Owen from Gargoyles. Stares at you blankly, silently judging you when you try to flirt.