Every Riot Fest is a cause for celebration, but now that the famed alternative festival is turning 21, it’s all the more reason to raise a toast and offer cheers, especially considering it’s yet another knockout line-up.

From Friday, September 18 to Sunday, September 20, a spread of local, national and global shapeshifters descends upon Douglass Park, which will feature around a hundred or so acts of countless underground persuasions to consider.

With that in mind, here’s ten carefully curated suggestions between the icons or up-and-comers who should prove to be worth the money and then some throughout this relatively reasonably priced annual tradition.

1. Patti Smith (Sunday)
Riding high off the 50th anniversary of her seminal debut “Horses” and knocking on the door of 80, “Queen Of Punk” Patti Smith heads home to show everyone she still sits atop the throne.

2. Iggy Pop (Friday)
As prolific as ever and gearing up for a similar milestone birthday, “Godfather Of Punk” Iggy Pop is destined to move multi-generations towards the mosh pit with his unquenchable “Lust For Life.”

3. Morrissey (Saturday)
Being the fabulous front man for iconic indie rockers The Smiths will always be enough to immortalize Morrissey, yet the enigmatic entertainer keeps churning out quality solo releases, such as the brand new “Make-Up Is A Lie.”

4. Alanis Morrisette (Sunday)
The only artist to ever make a “Jagged Little Pill” taste so sweet, Alanis Morrisette may seem like the alt-pop wildcard for this festival, but there’s no doubt she’ll be able to rock out like any of the heaviest hitters.

5. Nas (Saturday)
Hip-hop heads are bound to come out in droves to catch socially conscious rapper Nas, especially when it means they’ll get to hear classics from the autobiographical “Illmatic” masterpiece through today.

6. Sex Pistols (Friday)
Part reunion and half rebirth, The Sex Pistols are back after almost a couple decades apart starring original members Steve Jones on guitar, Glen Matlock on bass and Paul Cook keeping the beat, plus front man Frank Carter.

7. Public Image Ltd (Saturday)
Speaking of Sex Pistols singers/screamers, the estranged John Lydon (previously Johnny Rotten), turns to post-punk/experimental rockers Public Image Ltd, who are thankfully getting another run following the acclaimed “End Of World” album.
 
8. Twenty One Pilots (Friday)
The “Clancy” and “Breach” concepts have officially reached to a climatic conclusion, and as the live document tracing the international trek is titled, it was certainly “More Than We Ever Imagined” and worthy of an epic encore opportunity.

9. Angine de Poitrine (Saturday) 
Their papier-mâché masks and polka-dotted dress code has made Angine de Poitrine quite a mystery to unravel, though the Canadian duo will also hopefully live up to lofty expectations of its quirky experimental meets prog and math rock equation.

10. William Shatner (Sunday)
Since actor John Stamos’ appearance alongside The Beach Boys was such a success, it’s only fitting to find 95-years-young William Shatner of “Star Trek,” “Boston Legal” and “T.J. Hooker” fame cranking it up to 11 to debut his heavy metal band The F***ers in an absolutely oddball booking that’s as Riot Fest as it gets.

---

Riot Fest comes to Douglass Park from Friday, September 18 through Sunday, September 20. For additional details, visit RiotFest.org.