NEW YORK – “Don’t Look Back in Anger” seems to be fitting advice for the Britpop band Oasis, as they begin their unexpected reunion tour this week in Cardiff, Wales.

Fronted by brothers Liam and Noel Gallagher, this reunion signifies the resolution of the siblings’ notorious feud that led to the band’s 2009 breakup. For many enthusiasts, this development feels like a dream come true. They’re eagerly anticipating whether the Gallaghers will complete the full schedule of international concerts and possibly even continue beyond the planned tour.

Whether they commit for the long term or decide to part ways again sooner, let’s look at a few other notable — yet fleeting — band reunions.

The Beach Boys

DISBANDED: Technically, they never broke up. Read on.

HOW LONG THE REUNION LASTED: A few months in 2012.

WHAT HAPPENED: There is no linear history when it comes to The Beach Boys, but here’s the abridged: Band members came and went, and the band’s visionary, the late Brian Wilson, retired from touring in 1964 following a breakdown caused by stress and exhaustion. His place was soon filled by Bruce Johnston, who remained with the group for decades. Wilson also infamously feuded with his cousin and bandmate Mike Love over songwriting credits for years.

The question here is: Can a band that never broke up reunite? In this case, yes: The band — with both Wilson and Love — got together for a new album, “That’s Why God Made the Radio” and world tour in 2012, celebrating the band’s 50th anniversary. It wasn’t the whole original lineup, however: Drummer Dennis Wilson died in 1983, and guitarist Carl Wilson died in 1998.

CHANCES OF GETTING BACK TOGETHER: The force behind the band, Brian Wilson, died last month at age 82, but Love continues to tour under The Beach Boys name.

Led Zeppelin

DISBANDED: 1980

HOW LONG THE REUNION LASTED: Good question. The band played a few one-off events in the mid-1980s throughout the ’00s, never embarking on a reunion tour. So, a few days? A few hours?

WHAT HAPPENED: Led Zeppelin disbanded immediately following the death of drummer John Bonham in 1980, reuniting only for a select few events in the decades that followed. Most notably, their first show back was a complicated set at Live Aid in 1985 in Philadelphia. Their last performance together was in 2007 at the Ahmet Ertegun Tribute Concert held in London’s O2 Arena. There, Bonham’s son Jason Bonham played the drums.

CHANCES OF GETTING BACK TOGETHER: Highly unlikely. Lead singer Robert Plant and guitarist Jimmy Page have successfully evaded reunion requests in the past, including one from President Bill Clinton. In 2013, Clinton asked the British rock greats to get back together for the 2012 Superstorm Sandy benefit concert in New York City. He asked; they said no.

Nirvana

DISBANDED: 1994

HOW LONG THE REUNION LASTED: A series of one-off performances in the 2010s and 2020s.

WHAT HAPPENED: Nirvana disbanded following the death of frontman and principal songwriter Kurt Cobain. Its members pursued other projects — most notably, drummer Dave Grohl founded the Foo Fighters. But two decades after Cobain’s death, in 2014, Nirvana was inducted into the Rock & Roll Hall of Fame, so bassist Krist Novoselic, touring guitarist Pat Smear (of the Germs) and Grohl got together for a short set — joined by Lorde, St. Vincent, Joan Jett and Kim Gordon on vocals for a reunion dubbed “Hervana.”

CHANCES OF GETTING BACK TOGETHER: Maybe there could be a few more gigs here and there? Novoselic and Grohl reunited for a few one-off performances in the years that followed, most recently coming together for the Fire Aid benefit concert in Los Angeles and the 50th anniversary celebrations for “Saturday Night Live,” both this year. At the latter, Post Malone took over vocal duties.

Oasis

DISBANDED: 2009

HOW LONG THE REUNION IS SUPPOSED TO LAST: If the band makes it through their full run of reunion shows, July through November. So, five months.

WHAT HAPPENED: Good question. The band — and in particular, the Gallagher brothers — have not released a public statement giving specific reasons for the reunion. But the initial tour announcement did seem to allude to past tensions. “The guns have fallen silent,” Oasis said. “The stars have aligned. The great wait is over. Come see. It will not be televised.”

In 2019, Liam Gallagher told the AP he was ready to reconcile.

“The most important thing is about me and him being brothers,” he said of Noel. “He thinks I’m desperate to get the band back together for money. But I didn’t join the band to make money. I joined the band to have fun and to see the world.”

Fans had long theorized a reunion might be on the horizon, too: In the wake of the 2017 bombing that killed 22 at an Ariana Grande concert in Oasis’ hometown of Manchester, Liam Gallagher performed at a benefit concert. He criticized his brother’s absence, but a spokesperson said Noel Gallagher couldn’t attend because of a long-standing family trip. Benefit organizers said Noel Gallagher approved the use of Oasis’ music and donated royalties from “Don’t Look Back in Anger” to the British Red Cross’ One Love Manchester fund.

CHANCES OF GETTING BACK TOGETHER: It’s happening. A better question is: What are the chances of a new album? That’s impossible to know.

Outkast

DISBANDED: They never officially disbanded, so call it a hiatus. They never released another album after 2006’s “Idlewild,” and 2007 is frequently cited as the year they officially took a break.

HOW LONG THE REUNION LASTED: A few months in 2014? They announced reunion dates in January 2014, played their first in April, and ended that October.

WHAT HAPPENED: At the top of 2014, Outkast — the innovative Atlanta-based hip-hop duo consisting of Big Boi and André 3000 — announced they would tour festivals around the world to mark 20 years of their band, following a near-decade hiatus. The dates began at Coachella, where the duo headlined both Friday night shows. Then they made their way to their home state of Georgia for the CounterPoint Music & Arts Festival, which The Associated Press described as “an energetic show that kept the crowd jamming in the late hours.”

Once the reunion shows were done, so was Outkast. Big Boi continued to release solo records, and André 3000 would follow suit … almost 10 years later, when he released his debut solo full-length, the flute-forward “New Blue Sun,” in 2023.

“New Blue Sun” has “no bars,” he joked to AP shortly after it was released. It’s a divergence from rap because “there was nothing I was liking enough to rap about, or I didn’t feel it sounded fresh.”

CHANCES OF GETTING BACK TOGETHER: When asked about new Outkast music, André 3000 told AP, “I never say never. … But I can say that the older I get, I feel like that time has happened.”

The Velvet Underground

DISBANDED: 1973, more or less.

HOW LONG THE REUNION LASTED: A few months in 1993.

WHAT HAPPENED: Here’s another opaque one for you, as band reunions so often tend to be: John Cale was ousted in 1968, Lou Reed left in 1970 and the Velvet Underground slowly dissolved from there, releasing their final album in 1973, “Squeeze.” In 1990, Cale and Reed joined forces to release an album in homage to Andy Warhol, “Songs for Drella,” opening the door for a future reunion. There were a few one-off performances, and then the band toured Europe in 1993, including a performance at Glastonbury.

CHANCES OF GETTING BACK TOGETHER: It is pretty much impossible. Reed died in 2013. Guitarist Sterling Morrison died in 1995. And Nico died in 1988.