New series "Naked Vegas" on the Syfy Network takes us into the weird world of body painting. (David Becker/Syfy)

The years 1800 to 1860 are covered in the newest installment of “The African Americans: Many Rivers to Cross” (PBS at 8 p.m.). The burgeoning cotton industry leads to the expansion of slavery, but as slavery intensifies, so does resistance to it. The stories of Harriet Tubman, Richard Allen and Frederick Douglass are recalled.

Dorothy from Oz and the Wicked Witch make an appearance on “Supernatural” (CW at 9) when Sam and Dean try to locate an ancient computer in the Men of Letters house and dislodge a hex that unleashes a magical green-webbed wall. Dorothy became trapped in that web years ago, and now they have to stop the witch from escaping Oz.

In honor of its 75th anniversary, the original broadcast that sent radio listeners into a full-blown panic will be the focus of the special, “War of the Worlds” (PBS at 9). A 23-year-old Orson Welles narrated the H.G. Wells classic in 1938, leading listeners to believe that strange explosions were happening on Mars and that America was under a deadly Martian attack.

RETURNING SHOW: All four Roloff kids are back home for the first time in two years on the seventh-season opener of “Little People, Big World” (TLC at 9). The extra hands will help with wedding season approaching on the farm, but the family has to deal with two doses of tragic news.

RETURNING SHOW: We’re introduced to Curt, who has built an 80-acre off-the-grid estate equipped with a 3,000-square-foot greenhouse, a lake with one million gallons of water and a slew of infrared cameras on “Doomsday Preppers” (National Geographic at 9). Curt’s entire family helped design this fortress in the event of an economic collapse and they all happen to be trained in markmanship.

SERIES PREMIERE: Set on the Las Vegas Strip, “Naked Vegas” (Syfy at 10) will transport viewers inside the provocative and imaginative world of body painting art. Just in time for Halloween, the first episode follows the Naked Vegas Team as it plans an over-the-top zombie-themed wedding at Eli Roth’s Goretorium at Planet Hollywood.

Actor Rob Lowe and the 2013 Indy Car champion Scott Dixon join “The Late Show With David Letterman” (CBS at 11:35), along with musical guest Alan Jackson.

TV host Savannah Guthrie and businessman Mark Cuban visit “The Tonight Show With Jay Leno” (NBC at 11:35), with musical guest Kodaline.

Actors Jennifer Garner and David Arquette come to “Jimmy Kimmel Live” (ABC at 11:35), with a musical performance from Arcade Fire.

— Rachel Lubitz