Created in 1961 as a vehicle for Police Surgeon star Ian Hendry, The Avengers initially started life as a videotaped crime thriller in which Hendry's character, Dr David Keel, set out to avenge the murder of his fiance with the help of undercover agent John Steed.

With the departure of Hendry at the end of Season One, Steed was promoted to the series lead and, with the introduction of Honor Blackman as the leather-clad Cathy Gale, the series really started to take off. The first spin-off novel, simply titled The Avengers, was released soon afterwards.

When Honor Blackman decided to depart for pastures new at the end of Season Three, the nature of the series changed. Not only was Season Four to be made on film, but the more fantastic elements that had occasionally appeared in the Cathy Gale era were now brought to the fore, and the introduction of Emma Peel heralded the beginning of the most popular era of the show.

The new start for the programme also saw a number of new books being released. Patrick Macnee, with the help of Peter Leslie, wrote Deadline and Dead Duck which, apart from releases in Portugal, remained UK exclusives until the 1990s. John Garforth wrote four novels for Panther Books which were published in the UK as well as Chile, Holland, France, Germany and the USA — the only exception being Heil Harris! which wasn't published in Germany, for obvious reasons! With the sale of the series to the US, and a move into colour for Season Five, a further five novels, four with Tara King, were issued exclusively for the American market — none of which have ever seen print anywhere else.

The New Avengers in the mid-1970s spawned a series of novelisations, but no further original novels were published until 1977, when a fictionalised biography of John Steed was released. The early 1980s saw the appearance of a bootleg novel from Australia in the form of The Saga of Happy Valley. Despite it being unlicensed, it was allowed to remain on sale.

Everything then went quiet until 1990 when Avengers expert Dave Rogers collaborated with John Peel to write Too Many Targets. This featured most of the regular characters from the 1960s show (including the only printed appearance of Dr Keel) and is generally regarded as being the best of the original novels.

The release of the dismal Hollywood movie in 1998 starring Ralph Fiennes and Uma Thurman as Steed and Mrs Peel saw Too Many Targets getting a re-release via Tor Books. A novelisation and script book based on the film were also released. In France and Germany the John Garforth novels from the 1960s were also reprinted in omnibus volumes — the German edition (first published in the 1960s in hardback) again omitted Heil Harris! Rather disappointingly, none of the old novels were re-released in the UK.