It's possible he knew Ben, Richard and Eloise as they were all on the Island the same time he was. It's also likely he knew of the smoke monster aka The Man in Black.
Christian last saw his daughter when he visited her for the first time in many years when her mother was put into a coma after a car accident, he tried to persaude Claire to let her go but she refused. He tried to visit her sometime before his death but was not permitted by Claire's Aunt.
Christian met Ana Lucia at an airport in LA. He convinced her to fly to Australia with him as his bodyguard, she did so but they later went their seperate ways when Ana Lucia decided to return home to sort out her issues while Christian continued to stay in Australia and drink.
Boone and Shannon had met Paulo at the airport before boarding Flight 815. It's highly likely Boone had seen Paulo after this time too as he also survived the crash.
Boone was last seen speaking to Sayid when he approached Boone informing him that he and Shannon are getting closer. Boone warns Sayid away from her but he tells Boone he doesn't need his permission. This was the time when Boone also last saw Shannon on screen.
Locke had been with Boone when the beachcraft he was in fell from a cliff. Locke carried Boone to the caves but lied to Jack about how Boone had sustained his injuries. Locke then later vanished.
Both Jin and Charlie were told by Jack that he could not help Claire who was going into labour as he was trying to save Boone. He told them to tell Kate that she would have to guide Claire through it and also told them instructions on what to do.
Boone spent his last moments with Jack who had tried but could not save his life. Boone told Jack to "tell Shannon..." but he died before he could complete his last sentence.
Shannon was seen meeting Nikki after it was revealed Jack had a case of guns. It is also highly likely that she met Paulo too and that Shannon had seen them both again sometime before she had died.
It's likely Shannon saw all of them sometime before she died but it is unknown when as they were all busy spending most of their time in the Swan station.
Saw Walt mysteriously appear in the jungle, Shannon charged after him leading to her death. If the Walt she saw in the jungle was not Walt, then she last met Walt when he left on the raft.
Ana Lucia and Christian flew to Australia together so she could act as his body guard. They later went seperate ways when Ana Lucia decided to sort out her problems and go home whilst Christian decided to stay behind to drink. Later at the airport Ana Lucia over heard Jack talking about his deceased father, unaware that he was talking about Christian.
Ana Lucia along with Charlie and Sayid headed out to find Henry Gale's balloon in order to see if Ben was telling the truth about who he was. They discovered that he was lying.
Libby had met Ana Lucia early on the day they had both died, Ana Lucia told Libby that Ben had attacked her. Libby tells Ana not to do anything stupid.
Ana Lucia requested a gun from Sawyer but he wouldn't give her one. She later seduced him so she could then steal his gun from him in order to kill Ben.
Locke had rescued Ana Lucia earlier in the day when Ben attacked her. Ana Lucia last saw them when Michael returned to the hatch and told them that the Others aren't as powerful as they make out they are. Jack, Kate and Locke left to go and confront Sawyer for the guns leaving Ana in the hatch alone with Michael and Ben.
Last saw Ben when she handed him a knife in order to free himself, she however pointed a gun at him in an attempt to shoot him. But she couldn't bring herself to do so.
Michael persauded Ana Lucia to hand him the gun she had so he could kill Ben himself. However, as he had made a deal with the Others to release Ben to get his son back, he shot Ana Lucia and killed her instantly. He also shot and killed Libby when she walked in overseeing what he had done.
In the flash-sideways timeline Ana Lucia was a police officer who made a deal with Desmond to release himself, Kate and Sayid from imprisonment in exchange for money. Hurley asked Desmond if Ana Lucia was going to "move on" with them into the next life but Desmond told him that she wasn't ready to pass over and let go.
Libby met Desmond off-island in America. They had a cup of coffee together and Desmond told her he was going on a solo race around the world but was in need of a boat. Libby gives him the boat of her late husband, the Elizabeth. Coincidentally Desmond sailed back to the Island during Libby's funeral with that very boat.
Libby witnessed Bernard speaking to Boone over a radio and she heard his voice. By the time the tail section survivors merged with the other castaways Boone had died.
Most likely saw them a few hours before she died. Libby also helped Claire in remembering what happened to her when she was kidnapped by the Others. But it's highly likely Libby had seen and spoke to Claire afterwards as he death would not occur for several more days. Sun translated for Jin when she was looking for Hurley.
Met with Ana Lucia earlier on the day they had both died, Ana told Libby that Henry Gale had attacked her. Libby told Ana not to do anything stupid. Libby later walked in on Michael as he shot and killed her.
Last saw a seriously injured Libby under the care of Jack as Eko and Locke offered to go and hunt for Ben. Libby had passed away by the time Eko returned.
Nikki had likely met Jacob at some point in her life as she is listed as a Candidate. As Paulo's last name was never revealed he can't be assumed as a potential candidate.
They had met Ethan when he was pretending to be a survivor shortly after Flight 815 crashed. They most likely met him again sometime before he was exploited as a spy and killed.
Last saw Michael and Jack as they headed off to confront the Others. Jack was later captured by them and wasn't released until after Nikki and Paulo had died and Michael left the Island.
All of them presumed Nikki and Paulo were deceased and buried them alive. Rose and Bernard were not seen in the episode yet its highly likely they were present.
Michael last saw Jack, Kate and Sawyer after he betrayed them and left them captured in the care of the Others including Alex and left the Island with Walt.
Michael last saw his son as Walt looked through his window at the father he did no longer want to speak to after he confessed to killing Ana Lucia and Libby.
Michael last saw Tom off Island. Tom convinced him to join the Kahana crew as a spy for Ben. Later, Tom phoned him while he was boarding the freighter.
Last saw Frank and Sayid as they both left the Kahana the former on his helicoptor and the latter on a boat, both of them heading to the Island. Keamy ordered Frank to take him and his team to the Island.
Michael visited Hurley three years after his death as a ghost. He told Hurley that he needed to stop everyone from blowing up the plane otherwise it would get everybody killed. Hurley later saw Michael again who told him that the whispers were the sound of dead people who couldn't move on - including himself. He then told Hurley that if he ever sees Libby again then to tell her that he's very sorry for what he did. While alive, they met for the last time when Michael left the Island as Hurley was released by the Others.
In the flash-sideways timeline Charlotte was seen meeting and talking to all of them. She wasn't aware that she was dead and wasn't ready to move on. It's unknown when or if she ever did.
Last saw the Man in Black when he attacked the mercenaries in his Smoke form. It's also possible the "Christian" Locke encountered in "Cabin Fever" and "This Place Is Death" was the Man in Black as well.
Locke "moved on" to the next life with all of them.
Before his death Locke had never met Frank, Eloise, Penny or Ilana. He saw the Man in Black take on Christian's form, he saw Pierre on various orientation videos and he may of seen a young Eloise when he and his group were brought to the 50's.
Ironically, both Frank and Ilana were two of the four people at his funeral, despite never meeting.
Juliet last saw Horace as he was overthrown as the leader of DHARMA by Phil and Radzinsky who violently tried to force Sawyer and Juliet to tell them information about where and why Kate took the infant Ben.
Juliet, Kate and Sawyer last saw the three of them whilst running into them on their way to stop Jack from setting off Jughead, Bernard asked Juliet if she'd like to stay for some tea which she politely declined.
Ilana claimed Jacob was the closest thing she ever had to a father. She was last known to have seen Jacob at a hospital in Russia where he briefed her on how to protect the Candidates. She may have met or spoke to him after that however.
In the flash-sideways timeline Ilana worked as a Lawyer for Christian and Jack Shephard and Desmond Hume. Desmond introduced her to Claire Littleton who was in Christian's will and Jack and Claire met one another as brother and sister.
Sayid last saw Walt when he left the beach camp aboard his father's raft. Later, Sayid saw a vision of Walt in the jungle, just moments before Shannon's death.
Sayid last saw them all before he left the Island, when he returned Michael and Charlotte had died and Daniel died shortly after he was captured by DHARMA. Rose, Bernard and Vincent as of the Incidnent were retired in a hut in the jungle, but still alive.
Sayid fought with Keamy when he and Kate were asked to rescue Ben and was almost a match for him but Keamy over powered him and almost killed him but Sayid was rescued by Richard.
Sayid and the rest of the Oceanic Six, Frank and Desmond were all saved by Penny on her boat. Sayid last saw her when he left his boat and got back to his life.
Sayid last saw Cindy before The Man in Black's faction were attacked by Widmore's team, as Cindy wasn't seen at the beach when many people were killed it's likely she is alive, it was revealed in "The Candidate" that those who survived scattered into the jungle.
Sayid was seperated from him when Sawyer locked him and Claire out of the submarine. The Man in Black put a bomb into Jack's backpack and intended for Sawyer to lock him out. The bomb did detonate, killing Sayid instantly.
Jin last saw Naomi as she along with Jack and Rousseau led the survivors to the radio tower. Jin stayed behind to kill the Others who planned to attack their camp, Tom was the last Other killed during the battle.
Jin was forced to leave Michael with the bomb on the Kahana when Michael told Jin to get to Sun and take her home. The bomb killed Michael but Jin escaped.
Jin last saw both of them before Locke stopped the time flashes, Locke left the Island and Charlotte died. Jin had made Locke promise not to bring Sun or his child back to the Island, however Locke died and Ben brought her back anyway.
Jin was seperated from him when Sawyer locked him and Claire out of the submarine. The Man in Black put a bomb into Jack's backpack and intended for Sawyer to lock him out. The bomb did detonate, sinking the submarine and trapping Sun behind wreckage.
They were all on the submarine with him as it was sinking, Jin was present when Sayid sacrafised himself and Jin stayed behind to try and free a trapped Sun.
Sun was seperated from him when Sawyer locked him and Claire out of the submarine. The Man in Black put a bomb into Jack's backpack and intended for Sawyer to lock him out. The bomb did detonate, sinking the submarine and trapping Sun behind wreckage.
They were all on the submarine with her as it was sinking, Sun was present when Sayid sacrificed himself and Jin stayed behind to try and free a trapped Sun.