As I'd like this guide to be new reader friendly, I've avoided spoilers as much as possible. Anything that could still spoil is formatted in a darker colour, but they're still readable.

The Main Characters

Kathryn Janeway
Rank: Captain
Personality: Kathryn is the strong, stubborn and impulsive captain of Voyager. Normally she's an excellent captain who can talk down and scare away any menacing alien with her trademark death glare. She does have a good sense of humour, can be very friendly and comforting towards her crew. However she has a daily coffee intake that'll scare even the biggest coffee fanatic.
Birth Date: May 2331
First episode: Caretaker/Aggression

Rank: Commander (First Officer)
Personality: Chakotay is Kathryn's loyal first officer who always makes sure she knows when he thinks she's wrong. The two have very different command styles, so this happens a lot. He is very spiritual and usually calm, but when he's angry, it's best not to mess with him.
Birth Date: 2330
First episode: Caretaker/Aggression

Thomas "Tom" Eugene Paris
Rank: Lieutenant (Helmsman) / Lieutenant Commander / Acting Captain
Personality: Tom is the cocky, cheeky and fun loving helmsman. He has a habit of making any bad situation a little less tense with his humour, but that side of him can get him into trouble. He has a love for gossip and can't help himself when it comes to falling for women.
Birth Date: 2343
First episode: Caretaker/Aggression

Harry Kim
Rank: Ensign (Opps Officer) / Lieutenant / Acting Captain
Personality: Harry joins Voyager as an Academy Graduate; he's green, eager to please and will always follow the rules. He quickly makes friends with his opposite, Tom, and usually is his unwilling partner in crime. He is always willing to do the right thing, regardless of the situation.
Birth Date: 2349
First episode: Caretaker/Aggression

B'Elanna Torres
Rank: Lieutenant (Chief Engineer)
Personality: B'Elanna is the passionate and smart half Klingon Chief Engineer. When it comes to her job she really is one of the best. Her Klingon side is her worst enemy; mainly her quick temper.
Birth Date: 2347
First episode: Caretaker/Aggression

James Taylor-Stuart
Rank: Ensign (Security) / Lieutenant Security Chief / Acting First Officer
Personality: James will always tell you what he thinks, and he won't care about it either. Full of confidence yet conflicted with self hate. His temper has gotten him into trouble all his life and so has his sarcastic mouth. He can be emotional and defensive. If someone's in trouble he'll usually go out of his way to help them without any care for himself. Best friend Jessie is usually first on his priorities though.
Birth Date: July 2349
First episode: Caretaker/Aggression

Jessica "Jessie" Rex-Annet / Stuart
Rank: Crewman (Bridge Personell) / Tactical Officer
Personality: Jessie is known for her short temper and quirky behaviour, but there's more to her that she tries to hide. Once she lets people past her disguise of vanity and distrusting wall, they see her for how thoughtful and strong she is. Her skills to support (and amuse) work wonders on James, who she's been friends with since they were four.
Birth Date: October 2349
First episode: Caretaker/Aggression

Craig Anderson
Rank: Crewman / Lieutenant Security / Security Chief
Personality: Orphaned during a Marquis mission, teenager Craig had little choice but to stay with the Marquis. He begins as a shy young man, but with a tendency to blurt out what he's thinking and regret it soon after. During the years he grows confidence as he tries to find the perfect girl for him, but is it just a face? His meeting with Morgan changes his life forever.
Birth Date: July 2355
First episode: Caretaker/Aggression

Morgan */Lena
Rank: n/a / Acting Captain / Security
Personality: Upbeat, confident, and in your face. Morgan is the typical teenager when she joins the crew, despite her unique upbringing. A mystery from the start, Morgan still manages to fit in with the crew with her sunny, yet dangerous attitude to everything. Her charms manage to make womaniser wannabe Craig devoted to her from day one, and befriends the usually stubborn to new people James.
Birth Date: Unknown
First episode: Timeline

Rank: n/a
Personality: From a young age Kiara showed off her independence and fiery determination. Her emotions however can easily get the betters of her. As she is young, a lot of people see these qualities as bratty and spoilt. Her potential unrealised causes quite a stir amongst the crew, many times.
Birth Date: March 2373
First episode: Aggression

Rank: n/a wannabe villain
Personality: Damien is your typical cartoon/kids show villain: mad, laughs maniacally and is well... did I mention mad? His favourite things are: rabbits, laughing evilly, and yogurt. His reasons for always attacking Voyager are a mystery, everyone just assumes he does it for fun. His personality makes it impossible for people to take him seriously, however he is fiercely intelligent and can be keenly observant to things no one else is when he chooses to be.
Birth Date: Unknown
First episode: Ex Post Facto/Aggression

The Doctor
Rank: Chief Medical Officer
Personality: The Doctor is a hologram designed for medical emergencies, however the real Doctor and staff are killed in the first episode so he is forced to replace them. Over the years he develops his own programme, and becomes a real person in his own right.
Activation Date: September 2370
First episode: Caretaker/Aggression

Rank: Practicing Nurse
Personality: Kes is the sweet young Ocampan who joins with partner, Neelix. She at first is the sweet and innocent girl you can't help but like, but some of her new friends bring out a different side to her. She is always very curious especially towards medicine, so she becomes the assistant in Sickbay.
Birth Date: 2369
First episode: Caretaker/Aggression

Seven of Nine
Rank: n/a Astrometrics
Personality: Seven was assimilated by the Borg when she was only young. Now liberated she tries to get her individuality back. It's a difficult task, especially when nearly everybody can't stand her in the slightest. Seven can be pretty rude and act superior to everyone, even though she's not the only ex-Borg aboard. It all gets to her though and she slowly develops a different personality.
Birth Date: 2348
First episode: Aggression

Rank: Lieutenant / Lieutenant Commander Security Chief
Personality: Being a Vulcan, Tuvok is very calm and logical. He keeps his intense emotions buried deep within himself. Very intelligent he can provide an insight into every situation, and is a valuable asset to his close friend of many years, Kathryn Janeway.
First episode: Caretaker/Aggression

Rank: n/a ship's "chef" / self appointed diplomacy and morale officer
Personality: Neelix joins Voyager as their guide to the Delta Quadrant and as their chef. However not many of the crew enjoy his unique way of cooking and use the replicator instead, something he is strangely not aware of. He is usually very cheerful and at first critical of the Captain's decisions. He is madly in love with Kes and will do anything to keep her in his life.
First episode: Caretaker/Aggression

Regular Characters

Naomi Wildman
Danny Scott
Ian Richards
Ronnie Lavine * / Daniel Lavine
*Huge Spoiler* Ylara

Minor Characters

Claire Lewis
Lee Williams
Lisa Lillis
Triah Rise-Anderson
Phoebe Janeway
Sandi Clarke
Kevin Clarke
Jodie Harris
Jack Foster
Evil C/Clive
The FVDA regulars: Justin, Johnny, Myleene & Johnny Junior