I can think of several prog bands who have done this - "Flash" under former bassist Ray Bennett, Brand X's recent return, King Crimson (several times in fact), etc.  

When I lived in the UK, I saw a nice Scottish band, "Bis," from Glascow....they are not prog, but more in the Indie-power pop vein.  I saw them in 1994, and they dissolved.  However, they recently came back with a new album!! 

This single is so strong that I wanted to share it with Prog Archives.  It isn't exactly prog, but it is good.  I enjoy the composition, strong rhythms etc.  Reminds me a bit of progressive punk by Fripp et. al., I could easily hear one of his solos over this material. 

I'm in love with the new Gong LP.

Thanks!  I'm specifically thinking of a band that completely disappeared off the face of the earth for a long period of time, Gong and AD2 seemed to always be kicking around in the background (at least as long as Daevid Allen was around for Gong!). 

Brand X is having an especially energetic second coming, I highly recommend them.  Goodsall on guitar and Percy Jones on bass make this a strong comeback for sure.  

Other prog bands that have attempted to come back include Starcastle (meh, they never really got their mojo back), Dixie Dregs (I saw them in concert in the 1990s, they were excellent with ex-Mahavishnu violinist Jerry Goodman in the band), and the Strawbs (who have done concerts as acoustic and electric versions).  

Uriah Heep has come back with a surprisingly strong sound!  I passed on a chance to see them at a local bar & after seeing some video, regret not having went to see them.  Andy Powell's version of Wishbone Ash is also convincingly strong. 

siLLy puPPy wrote:   I wish bands like Yes, Pink Floyd and PFM would just give it up already.

I'll never get this opinion. If you don't like what they're doing now, don't listen to it. Not that I'd love what these bands have done recently (The Endless River is fine by me though, and then actually PF have given it up in the meantime), but as long as they and a handful of listeners have their fun, they should absolutely go on to do whatever they love doing.  

Far Corner had two good albums in 2004 & 2007 then a long gap to the superb Risk in '18.

Comus had a superb debut in First Utterance in '71 then a not so special follow up in '74 then nothing until '12!! With a really quite good appropriately named Out Of The Coma.

Dirk Mont Campbell of Egg, Gilgamesh & National Health released his debut solo album in '96, the follow up wasn't until '09.

Anglagard released two great album in 92 & 94 then nothing until the great Viljans Oga in '12

Happy Family release two albums in '95 & '97 then the quite excellent return with Minimal Gods in '14 with a great RIO performance

Of course, Claudio Simonetti left again, and the other four (Morante, Pignatelli, Guarini, Marangolo) have recorded a couple great albums as [Backtothe]Goblin (plus Goblin Rebirth with Pignatelli/Marangolo), while Claudio plays Goblin classics with his band Daemonia. Goblin (with Simonetti) did manage to perform a number of US dates, but Claudio left again, with Simonetti's role having been represented since on numerous live dates by Zombi's Steve Moore (one tour only) and then Goblin Rebirth's Aidan Zammit.

Last year, Claudio released a double live album, a performance of Goblin's classic soundtrack to Dawn of the Dead, under "Claudio Simonetti's Goblin." It was dedicated to George A. Romero.

The point is: It's a great time to be a Goblin fan!

That's it! I couldn't imagine Banco without great Francesco Di Giacomo, but 2019 album looks like their best studio work since "Canto di primavera" (1979).

Starcastle (whom I knew) came back briefly, check this nice little song out....a tribute to the late, great Gary Strater, one of the fine prog bassists!  The vocals sound just like Jon Anderson...!

Horslips...after 24 years apart....their 2004 comeback album Roll Back

Another one came to me = Captain Beyond.  After three very good LPs, they disappeared.  

CB did resurface in 2001 (I was helping the band in their comeback), but they couldn't find any traction for funding, and key members stayed away.  

CB is still trying, with founding drummer Bobby Caldwell holding down the fort.  I think he's having a tough ride with it, as the musicians are not nearly up to the quality of the founders, Rhino Reinhardt and Lee Dorman.  

RIP Rhino and Lee!

They tried a re-boot with Paul Rodgers, and then again (recently) with Adam Lambert!  

Talk about a band that won't go away!  I was a huge fan of their first 3 LPs, and then, meh...

Regarding Comus, while I like Out of the Coma, I actually prefer To Keep From Crying (I seem to be a bit of an oddball for one who, at least mostly, really enjoys that album, especially when taken as part of the Song to Comus: The Complete Collection Compilation album).  Perhaps had I got that album not as part of the compilation, I might never have gown to enjoy it as much.

As for Out of the Coma: Had "The Malgaard Suite" been remade (and perhaps kept the original as a bonus track), I think it could have been a much better album.  I do like "The Return" considerably even though I would rather another woodwind to the sax.  I find the rest hokey and too over-the-top often, and the album rather too "Comus-by-numbers".  I feel like it's aimed too much at just pleasing/ paying lip service to the First Utterance fans rather than a really inspired, creative album that shows growth.   It rather comes across as a tribute act of itself to me. 

Sticking with folk, but an artist rather than a band, but I liked Vashti Bunyan's return with 2005's Lookaftering, which I find a very enjoyable album.  Her last album before that was 1970's "Just Another Diamond Day(so 35 years).  Lidna Perhacs, who released the one album, which I think excellent in 1970 as well, Parallelograms, had  a comeback in 2014 called The Soul of All Natural Things (44 years in between albums).  I haven't listened to all of that, but what I heard I didn't enjoy (it's not acid folk, but instead it's contemporary dream pop folk).  I guess I would have enjoyed it more had she catered to fans of her "Parallelograms" music.

EDIT: I may have missed it, but did no one mention Bubu?  Anabelas was released in 1978, and Bubu only came back in 2018 with El Eco del Sol.

I'm not really sure either of those incarnations were taken too seriously. I mean Queen without Freddie just isn't. That's not too understate the talent of the other guys (and they are seriously talented) but I can't think of any other 'genuine band' where one member was so hugely important. BTW my favourite Queen album is probably Innuendo.

All valid points on Out Of The Coma but I must admit being baffled by preferring To Keep From Crying over First Utterance, all credibility lost 

Actually, I did see an amazing one - Deep Purple in 1985 in Tokyo - Destiny Brought Them Together Again and I got to see and hear it!

It Bites: nothing from 1989 to 2008, and then the magnificent Tall Ships

Shame they have now split up for good it seems....

Thanks for the input!  I saw a pre-Brand X reunion in December 2001 with John Goodsall, Percy Jones, vibraphonist Marc Wagner and an excellent drummer at a very small venue in Chicago!  I kept in touch with Goods, and he went back & forth from failed projects (one of which might have included Patrick Moraz!), rotten country-rock cover bands in Minnesota, and finally the revamp of an amazing version of Brand X, true to its form!  

I also saw the rebirth of Dixie Dregs in Chicago....this band featured famed Mahavishnu Orchestra violinist Jerry Goodman, and they were remarkable!  I think it was about 1994 or so, and again, in Chicago. 

I saw Gong TWICE (two consecutive nights) at (eh) ANOTHER small venue in Chicago....being able to see the late Daevid Allen, Bloomdido & everyone was a dream come true!  Hearing material from "You" in the early 1990s was unreal!  

It is certainly worth keeping your eyes open for summer festivals, band websites and the like, to see who may be coming back.  The Arcada Theater outside of Chicago is famous for booking top-shelf prog acts, I see that Grumpy Old Rick Wakeman will be there in October 2019!   Cheers, everyone! 

Colosseum is another favorite band,  reuniting in 1994 in the UK to acclaim and toured on and off since then in the UK and Europe, but was dealt a big blow with the death of drummer Jon Hiseman, more recently. Colosseum itself is no more, but there exists a tribute band with Clem Clempson and Mark Clarke at the helm currently.

With painful honesty, my other favorite bands will never make a comeback, I am pretty sure; Triumvirat, Giger Lenz Marron, Libra and Dzyan. In those cases, to make a long story short, it's not in the cards....