Coulter, the acid-tongued conservative with a new book out, and Carlin, the quick-witted, antiestablishment comedian who's in the voice cast for the new animated film "Cars," were booked at separate times for the NBC late-nighter, a spokeswoman said Monday.
But the duo's meeting could produce serious fireworks for "Tonight," which usually limits its political fodder to Leno's bipartisan monologue jokes.
Coulter, author of "Godless: The Church of Liberalism," has drawn fire for attacking the four New Jersey widows who pushed for an independent commission to investigate the Sept. 11 World Trade Center attacks in which their husbands died.
In her book, Coulter accuses the women of "reveling in their status as celebrities and stalked by grief-arazzis. I've never seen people enjoying their husbands' deaths so much."
An appearance by Coulter on another NBC series, "Today," led to a prickly exchange with host Matt Lauer over her comments on the widows.
Also scheduled for "Tonight" Wednesday is Scottish singer and songwriter KT Tunstall.