Diamond returned to Bayside High as Principal Belding's assistant in The New Class episodes, remaining with the show until its cancellation.

During his run on the show, he came into conflict with former American Idol finalist Kimberley Locke, country singer Cledus T. Judd, rapper Da Brat, the program's host Ant, and the program's trainer, former USMC sergeant Harvey Walden IV.

[11] Following Celebrity Fit Club, Diamond played roles as "Alumnus Guy #1" in American Pie Presents: The Book of Love (2009), in a supporting role in the sports comedy Tetherball: The Movie (2010), and as Bernardo, the castle guard, in the partially-animated science fiction comedy Hamlet A.D.D.

[10] In 2009, Diamond published an inside story of the show's cast and crew, from his point of view, titled Behind the Bell.

He claimed that many parts of the book, such as allegations of teen sex and drug use, were fabricated from very minor statements he made during the interviews.

In other commercials, he is shown to be pulled over, not caring about the already numerous tickets he has because he is “saved by the King!”,[22] being in a Western style standoff,[23] and being a terrible barber.

[27] Diamond was a special guest referee for a match at Celebrity Big Bang Wrestling, Mistress Devon James vs Susan Finkelstein on July 22, 2010.

[25] On February 11, 2011, Diamond teamed with Jordan McEntrye and Knight Wagner, losing to MsChif, Marion Fontaine and Krotch in an intergender match at AAW in Merrionette Park, Illinois.

On March 17, 2011, he teamed with Bushwhacker Luke, Izzy Slapawitz and Doink the Clown to beat Virgil, Ashley Sixx, Celine Jean and Sheena at TWE Rethinking Rumble in Vaughan, Ontario.

He lost his final match in a tag during the main event of FTW Summer of Synn, in Ronkonkoma, New York, on July 7, 2012.

[28] On June 13, 2006, he asked listeners of The Howard Stern Show to visit his website and purchase a T-shirt, reading "I paid $15.00 to save Screeech's house" (spelling "Screech" with an extra E for copyright reasons).

[32][33] On December 26, 2014, Diamond was arrested in Ozaukee County, Wisconsin, for possession of a switchblade knife, which he was alleged to have pulled during a bar altercation in which a man was stabbed.

[41] Despite completing one round of chemotherapy in Cape Coral, Florida,[42] he died from the disease on February 1, 2021, at age 44.