This collection lists, in movie timeline order (although some films overlap), all the Marvel Studios films that lead up to, and spin off from, the multi-character Superhero epic 'The Avengers' aka 'Avengers Assemble'.
Marvel have gained the rights back to Iron Man, Hulk, Captain America, Thor and Ant-Man. These characters were the classic line-up of The Avengers.
This list shows how the individual movies reference each other and establish that these characters all live in the same shared Marvel Cinematic Universe or MCU.
This list works on the assumption you have seen all the MCU films up to and including Ant-Man and The Wasp, the TV shows Agent's of S.H.I.E.L.D (up to and including S5), Agent Carter (S2), Runaways (S1)…