In 1964 DC Comics recognized that Batman needed some shaking up. During the reign of Jack Schiff at Detective (265-326) and Batman (122-163), the character had become moribund, regularly facing aliens and monsters and undergoing weird transformations. Like Superman, he had begun to acquire a "family"--Robin in 1940, Alfred in 1943, Batwoman in 1956, Bat-Mite (a magical pixie) in 1958, Bat-Girl (the first one) in 1961, and perhaps the most annoying of all, Ace, the Bat-Hound in 1955.
So after replacing Schiff as editor of the two titles with Julius Schwartz, DC eliminated almost all of the supporting cast. Robin was allowed to remain, but Batwoman, Bat-Mite, Bat-Girl and Ace were all banished to the dustbin of history, with no goodbyes or explanations. Much like discredited former Soviet leaders, they were airbrushed out of the picture. Alfred got a hero's send-off as he was crushed by a boulder while saving Batman and Robin.
There were several more major changes. First, there were no more aliens or monsters (mostly) or weird transformations. And DC continued to bring back Batman's villains from the Golden Age. In 1963 they brought back the Penguin; in 1965 the Riddler made his first appearance since 1948.
The death of Alfred in Detective #328 resulted in one addition to the Wayne household. Dick Grayson's Aunt Harriet joined the lads, reportedly added by DC in order to quash once and for all the rumors that Batman and Robin were gay (a theory originally proposed by a quack psychiatrist in Seduction of the Innocent, an early 1950s expose on the comics' sometimes seamier side). Although remembered by many comic fans as being inspired by the TV show, Aunt Harriet actually predated the debut of the ABC series. If anything, it was the show that resulted in the return of Alfred, the faithful butler, who was resurrected in Detective #356.