This list is for anyone who wants to know the order of each piece of media. The Alien Versus Predator (AVP) movies are no longer canon. This list does not include most of the Aliens comics, as it is hard to find comics that remain as canon ever since Ridley Scott changed it (like Disney did with Star Wars). This list is the best so far for continuity. The series was almost rebooted with a cancelled sequel that would have changed everything after Aliens (film). A theory later emerged that the Blade Runner series (including Blade Runner, Soldier, and Blade Runner 2049) is in the same universe as the Alien series. Since then, Ridley Scott has confirmed this theory and thus it is now part of the timeline.
Billions of years ago - one Engineer sacrifices himself to seed Earth with the building blocks of life.
1990 AD - Sir Peter Weyland is born.
1996 AD - A new military program to get orphaned infants and give them a lifetime of training is initiated.
2019 AD - Events of Blade Runner (Film).
2022 AD - A major blackout occurs after a group of rebels unleashed a massive EMP that wiped out all data world wide.
2036 AD - Neander Wallace introduces his new Replicant model.
2036 AD - Events of Soldier.
2049 AD - Events of Blade Runner 2049.
2089 AD - An Elizabeth Shaw memory from that time is shown in a memorial device system seen by David in Prometheus.
2090 AD - Peter Weyland dictates a letter reminiscing about his mentor Eldon Tyrell and their competition in the field of artificial intelligence.
2093 AD - Major occurrences in the Prometheus Expedition.
2104 AD - Happenings from Alien: Covenant .
2122 AD - Happenings from Alien.
2137 AD - Happenings from Alien: Isolation aboard the Sevastopol Space Station.
2179 AD - Ripley is rescued from the Outer Rim.
2179 AD - Ripley is taken to Gateway Station.
2179 AD - Happenings from Alien 3.
2381 AD - Major happenings from Alien: Resurrection.
*For comparison, most events in the Starship Troopers franchise are set in the 2300s AD.