Thankfully, not every character you encounter in Half-Life 2 is out to make you dead. Here's a few of the less hostile people you'll run across.

Gordon Freeman Playable Character In Half-Life 2, you are Gordon Freeman, a former Black Mesa researcher who somehow re-invented himself as an one man army. Half-Life 2 assumes Gordon accepted the G-Man’s offer to work with him at the end of the original game, and he’s been working under the G-Man’s watchful eye for an unspecified amount of time.

Alyx Vance Side-Kick Alyx is a prominent member of the resistance against the Combine, and is the gifted daughter of scientist Dr. Eli Vance. Alyx has inherited an aptitude for science and is great with all things technological; she works closely alongside her father and Dr. Isaac Kleiner in their teleportation experiments. Growing up fighting Combine rule has also made her skilled at combat, and she can help Gordon out of some tight spots with her trusty automatic pistol and her formidable pet robot, Dog.

Barney Calhoun Former Black Mesa Security Guard Barney was formerly a security officer at Black Mesa, where his friends included Gordon Freeman and Dr. Isaac Kleiner. Whenever Isaac locked himself out of his own office, Gordon and Barney raced each other through the air duct system in order to retrieve the keys. Barney fought his way out of Black Mesa early during the disaster, and later was lucky enough to meet up with fellow survivors Isaac, Eli and Alyx. Though Barney lacks the scientific expertise of the other Black Mesa escapees, he has a vital role in the resistance working undercover in the Civil Protection police force.

Dr. Isaac Kleiner Former Black Mesa Scientist A brilliant but absent-minded scientist, Dr. Isaac Kleiner once had an important position at the Black Mesa Research Facility. Before Black Mesa, Isaac was Gordon Freeman’s professor at the Massachusetts Institute of Technology, and in fact it was Isaac that recommended Gordon for the research associate job in the Anomalous Materials Laboratory. Isaac is now a linchpin of the resistance against the Combine, and his secret laboratory in City 17 contains a sophisticated teleportation machine. He keeps a debeaked headcrab (named "Lamarr”) as a pet, just one of his many eccentricities.

Dr. Eli Vance Former Black Mesa Scientist Eli worked with Gordon at Black Mesa, where he also lived with his wife Azian and their young daughter Alyx. Eli was able to rescue Alyx when the accident occurred, but he lost both his wife and his leg during the disaster. He later built the robot Dog to ensure Alyx's protection. Eli now has his own advanced teleportation laboratory at the resistance’s main base of operations, named Black Mesa East. The last time you saw Eli was just after the resonance cascade, when he asked you to head to the surface for help; now you can help him out in the struggle against the Combine.

Dr. Judith Mossman Former Black Mesa Scientist Another scientist for the resistance, she works closely with Eli on teleportation technology at Black Mesa East. Unlike the other scientists, she was not employed at Black Mesa, though she was a colleague of theirs. If it were not for Gordon’s experience at Innsbruck, Judith would have had his research associate position. Judith is clearly very fond of Eli Vance, but she does not get on well with his daughter Alyx, and disapproves of her more relaxed attitude to science.

Father Grigori Crazed Ravenholm Survivor A Russian Orthodox priest, Father Grigori once ministered to the inhabitants of Ravenholm. After the Combine shelled the town with headcrab-filled canisters, he decided to save the people’s souls by killing the zombies they had become. The traumatic experience seems to have left Grigori a little unhinged, making him prone to mad fits of maniacal laughter. As well as blasting zombies with his shotgun Annabelle, Grigori has also set up a variety of lethal traps throughout the town, to dispatch whole groups of zombies and headcrabs at once. You can also make use of these traps—just be careful not to fall into them yourself.

Col. Odessa Cubbage Resistance Leader Colonel Odessa Cubbage runs the resistance’s operations along the coast, from a base known as "New Little Odessa”. He has an upper class British accent and wears military ribbon bars on his jacket, but some resistance members doubt the authenticity of his accent, or his supposed military accomplishments. Regardless of his quirks, he knows what he is doing; he’ll instruct you on how to use laser-guided rockets to take out Combine gunships.

Citizens Civilian Populace Among the oppressed inhabitants of City 17 there is a significant underground movement; even citizens that aren’t actively involved in the resistance are usually sympathetic. Gordon has gained an almost messianic reputation since the Black Mesa incident, and as you strike blows against the Combine you’ll find the entire population of City 17 rooting for you. Citizens can be armed with pistols, submachine guns, shotguns, Combine pulse-rifles or even rocket-propelled grenade launchers. Later in the game they’ll form squads that will follow you around and take orders.

Resistance Fighters Human Militia This hardcore militia has abandoned the pretence of citizenry and is comprised of full-time rebels. They wear the lambda symbol, which has been adopted as the resistance’s banner. Resistance squads will fight by your side, armed with submachine guns, shotguns, Combine pulse-rifles, or occasionally a rocket-propelled grenade launcher. Many resistance fighters will be happy to supply you with any ammo you are short of if you approach them. Some members of the resistance act as medics and wear a red cross; if you are injured they will fix you up with a medkit. When in your proximity you can order them around.

Vortigaunts Allied Xen Beings The last time you saw these alien beings they were slaves of the Nihilanth. Part of the invasion from Xen, they had a tendency to try to zap you with blasts of green lightning. When you killed the Nihilanth you freed the Vortigaunt race—until the Combine came along and enslaved them again. As a result, the Vortigaunts have joined the resistance movement; their telepathic abilities and mastery of electricity makes them great fighters, scientists and engineers. If you talk to a Vortiguant, occasionally one may be willing to impart some energy into your HEV suit.

Dog Alyx's Pet Robot Both a robot pet and mechanical bodyguard, Eli built Dog to protect Alyx when she was still young. His face and eye are made up of parts from a Combine scanner. Eli and Alyx have added to him over the years, so as Alyx has grown, Dog has too, and he has become a formidable fighting machine. Dog’s sophisticated artificial intelligence has similarly developed over time, and he can understand tricky situations and undertake complex tasks. He even appears to possess emotions, and seems very protective of Alyx—something a few Combine soldiers might be unlucky enough to discover first-hand.