Six series of The Avengers were made between 1961 and 1969. There was an enforced break in filming and transmission towards the end of series five due to financial problems. Television researcher Andrew Pixley and authors Paul Cornell, Martin Day and Keith Topping in their book The Avengers Dossier: The Unauthorised and Unofficial Guide consider the last eight episodes produced after the break as constituting a short series six, and therefore count seven series in total. Within the internal production of The Avengers the last eight episodes were considered to be a continuation of series five.

Wikipedia lists season 5 and 5.5 together as a single complete season 5 with season 6 being the final season, while IMDB lists them as a partial season 5 and very short season 6 respectively. IMDB lists the final season as being season 7.

The episodes listed in this Season 5 folder contain S05E01 through S05E16 and the season 5.5 folder contains the rest of season 5 with the episodes in that folder being named S05E17 through S05E24. I split the season 5 episodes into 2 different folders to make the distinction noted above in the first paragraph.