Set to debut on the broadcast network April 9 at 9 PM ET (check local listings), the new hour-long series will feature Grier as host with "The Kids in the Hall" alumni Dave Foley ("News Radio") as judge.

Stage alum Jason Alexander and Richard Kind — both veterans of The Producers — will appear as will Ana Gasteyer (Wicked), Fran Drescher (Some Girl(s)), Eddie Kay Thomas (Smelling a Rat) and Wendie Malick (Burleigh Grime$).

Also set to guest star are Jennifer Coolidge ("For Your Consideration"), Bryan Cranston ("Malcolm in the Middle"), Joel McHale ("The Soup"), Tom Arnold ("Best Damn Sports Show"), Fred Willard ("Best in Show"), Nicole Sullivan ("Mad TV"), Angela Kinsey ("The Office"), Kurtwood Smith ("That 70's Show"), George Takei ("Star Trek"), Shannon Elizabeth ("American Pie"), Wayne Knight ("Seinfeld"), Kevin Nealon ("Weeds"), Bill Bellamy ("Last Comic Standing"), Jane Lynch ("For Your Consideration"), Edie McClurg ("Ferris Bueller's Day Off"), Brian Poeshn ("The Sarah Silverman Program"), Harland Williams ("Dumb & Dumber") and comedians Paul Rodriguez, Tom Green, Chelsea Handler and Mo'Nique.

NBC ordered six one-hour episodes of the show from FremantleMedia North America (producers of "American Idol") based on that company's other versions of the show airing across the globe.

According to notes, "'Thank God You're Here' showcases the improv skills of a group of four brave actors each week, as they walk into the high wire act known as improv, into a live sketch without a net – or script, their only armor and motivation is an unforeseen and unexplained wardrobe change. The only thing the celebrity can count on when walking into the scenario is a desperate greeting from a fellow actor in the skit, proclaiming upon their arrival, 'Thank God You're Here!'" "Thank God You're Here" is currently produced by FremantleMedia in The Netherlands, Germany, Russia, Sweden, the U.K., Portugal, Belgium, Norway, Israel, Denmark and Australia — where it originated and currently plays in its third season.

Seen at La Jolla Playhouse last fall in The Wiz, Grier appeared on Broadway in the lead role of Pseudolus in the revival of A Funny Thing Happened on the Way to the Forum. His Broadway debut came in the musical The First, as baseball great Jackie Robinson — which earned the actor a Tony nomination. He also played in the short-lived musical version of The Mambo Kings. The comedic actor is known for his roles on television in "In Living Color," "Life With Bonnie" and in the films "The Woodsman," "15 Minutes," "Return to Me," "Jumanji," "Boomerang" and "Bewitched."