2001–2008: post-reunion
On the eve of the Japanese and Australian leg of the Farewell Tour on January 31, 2001, Criss suddenly left the band once again, because he and the band could not come to agreement with his contract salary. Taking his place was previous Kiss drummer Singer who assumed Criss's Cat persona as the Farewell Tour continued.
With the band supposedly set to retire by early 2001, a career-encompassing collection entitled simply The Box Set, consisting of 94 tracks on five CDs, was released in November of that year, while the summer saw perhaps the most outrageous item of Kiss merchandise yet – the Kiss Kasket. In introducing the Kiss Kasket, Simmons quipped, "I love livin', but this makes the alternative look pretty damn good."
On December 4, 2001, Kiss was one of the honorees at the National Academy of Recording Arts and Sciences ("The Recording Academy") Heroes Award ceremony, at the NARAS New York Chapter. NARAS has 12 chapters throughout the United States, hence 12 ceremonies throughout the year, with the honorees each being honored by the chapter closest to their residence. By receiving this honor, which NARAS has renamed the "Recording Academy Honors", Kiss effectively received NARAS's second-highest career honor, right behind the Lifetime Achievement Grammy Award.
Kiss was relatively quiet through the rest of the year, but 2002 started with some controversy as Simmons took part in a controversial interview on National Public Radio with host Terry Gross. In February 2002, Kiss (with Singer on drums and Frehley on lead guitar) performed during the closing ceremony of the 2002 Winter Olympics in Salt Lake City, Utah which was Frehley's final performance as a member of Kiss.
On March 6, 2002, Kiss performed a private concert at a resort in Trelawny, Jamaica. Frehley, who was no longer under contract, did not perform with the group. He was replaced by Thayer, who donned Frehley's Spaceman makeup and costume for his first live appearance with Kiss. That month, the band (with Thayer) taped an appearance on the American sitcom That '70s Show. The episode, "That '70s Kiss Show", aired in August 2002. Thayer again performed with the group in April 2002, when Kiss performed "Detroit Rock City" (with pre-recorded music and live vocals) for an appearance on Dick Clark's American Bandstand 50th Anniversary show, which aired on May 3.
In February 2003, Kiss traveled to Australia and recorded Kiss Symphony: Alive IV with the Melbourne Symphony Orchestra at Marvel Stadium (then known as Telstra Dome) in Melbourne. Thayer once again replaced Frehley, while Criss returned to the group, as one of the conditions set forth by promoters required the band's lineup to include at least three original members.
Despite claims made prior to the Farewell Tour that it would be the group's last, Kiss toured with Aerosmith in 2003. Frehley announced that his departure from the band was permanent, stating that he believed the Farewell Tour would be Kiss's last, and declined Simmons's invitation to join the band on the Aerosmith tour. He was permanently replaced by Thayer, as Kiss moved into a post-reunion phase that saw the band easing into a new lineup, permanently featuring Thayer as "Spaceman" and Singer as "the Catman". On this tour, still featuring Criss, the group introduced the "Platinum" tickets package, with the most expensive packages costing $1,000. This package included a seat in the first five rows, a meet-and-greet with Kiss after their performance and a photograph with the band. The tour earned more than $64 million in 2003, which ranked seventh for the year.
Simmons and Stanley did not renew Criss's contract when it expired in March 2004. Criss, on his website, stated that "No one, again, no one has called me, or my attorney about an extension for future touring. As a founding member I find this to be disrespectful to me, and to the fans that have made us one of the biggest bands in the world." Eric Singer once again replaced Criss.
In mid-2004, Kiss headlined the Rock the Nation 2004 World Tour, with Poison as the opening act. The tour ended in August with a sold-out show in Mexico City. Selected dates on the tour were filmed for the Rock the Nation Live! concert DVD, released on December 13, 2005. Stanley, who had been experiencing increasing difficulty with his hip, had his mobility limited during the tour. He has already had two hip surgeries performed, with more likely in the future.
After the conclusion of the Rock the Nation Tour, Kiss performed only sporadically for a number of years. The group played two shows in 2005, and another six in 2006. Four of the 2006 shows were July concerts in Japan, including two dates (July 22 and 23) as a headlining act at the 2006 Udo Music Festival. Kiss performed four July 2007 concerts, three of which were dubbed the Hit 'N Run Tour. Prior to the final show on July 27, Stanley was hospitalized with an extremely rapid heartbeat. In his absence, Kiss performed in concert as a trio for the first time since 1982. This was the first Kiss concert that Stanley had missed during his then 34-year tenure with the group.
Kiss (along with Queen, Def Leppard and Judas Priest) were honored at the inaugural "VH1 Rock Honors" event, held May 25, 2006, in Las Vegas. In June 2006, Simmons and Stanley attended the opening of the Kiss Coffeehouse in Myrtle Beach, South Carolina. On October 15, 2006, Simmons, Stanley and Criss were inaugural inductees into the Long Island Music Hall of Fame, along with performers such as Neil Diamond, Billy Joel, Louis Armstrong, the Ramones and Tony Bennett.
Stanley released his second solo album, Live to Win, on October 24, 2006, and undertook a brief solo tour in support. On October 31 the same year, the group released Kissology Volume One: 1974–1977, the first of 10 possible DVD sets featuring complete concert footage, interviews and never-before-seen clips. By January 2007, the set had been certified 5× Platinum in the United States. A second volume was released on August 14, 2007. It was certified 6× Platinum by the RIAA on October 24. What seemed to be the final entry, Kissology Volume Three: 1992–2000, was released on December 18, 2007, and has been certified 8× Platinum by the R.I.A.A.
In April 2007, former guitarist St. John died from an apparent cerebral hemorrhage at age 51. After being forced to leave Kiss in 1984, St. John formed the short-lived glam metal group White Tiger.
Though Kiss had been eligible for enshrinement in the Rock and Roll Hall of Fame since 1999, they were not nominated until 2009 and were not inducted until 2014. While this snub displeased some fans, Stanley and Simmons maintained that it was meaningless to them. Nevertheless, a group of about 200 Kiss fans held a protest rally in front of the Hall of Fame in Cleveland on August 5, 2006. It was the first known organized demonstration seeking the induction of a band into the Hall.
In 2007, a new comic book series featuring the band was released by the Kiss Comics Group in association with Platinum Studios, titled Kiss 4K: Legends Never Die.
The band picked up their pace in 2008, embarking on their first proper tour of Europe in nearly a decade. On January 30, 2008, Stanley confirmed that Kiss would launch the Kiss Alive/35 World Tour, playing arena and stadium shows in Europe, Australia and New Zealand. On March 16, 2008, Kiss closed the Australian Grand Prix at Melbourne Grand Prix Circuit as well as performing in Brisbane and Sydney as part of this tour. Kiss played at the Rock2Wgtn two-day festival held in Wellington, New Zealand, on March 22 and 23, 2008; the festival also featured Ozzy Osbourne, Whitesnake, Poison, Alice Cooper, Lordi, Sonic Altar and Symphony of Screams, with special effects provided by WETA Workshop (of The Lord of the Rings and King Kong fame).
Throughout the summer of 2008, Kiss headlined festivals as well as their own shows and played to a record audience of about 400,000 people. As part of this tour, Kiss headlined the Download Festival at England's Donington Park on June 13. Three days later, they headlined the Arrow Rock Festival in Nijmegen, Netherlands. On June 28, Kiss headlined the Graspop Metal Meeting in Dessel, Belgium. It was the last show of the European leg of the Kiss Alive/35 Tour. On August 4, Kiss played at Rockin' the Rally at the Sturgis Motorcycle Rally as part of the tour. South Dakota Governor Mike Rounds proclaimed August 4, 2008, to be "Kiss Rock and Roll Day" in South Dakota. In September 2008, both Simmons and Stanley confirmed rumors that the Kiss Alive/35 Tour would continue with extensive tours of North America in the beginning of 2009, as well as South America. The latter tour included shows on April 5 in Argentina, April 7 and 8 in Brazil, April 11 in Colombia, April 14 in Peru, and other concerts in Venezuela and Chile. That summer, Kiss came back to North America to continue the Alive/35 World Tour, starting on July 18 in Halifax, Nova Scotia.