US TV
Rex Features
The 50-year-old will appear on the USA Network drama for a two-episode stint, says The Hollywood Reporter.
Janney has been cast in the role of a newly-appointed US Marshall who disagrees with Mary (Mary McCormack).
The actress is also due to co-star in Matthew Perry's ABC comedy Mr. Sunshine and in forthcoming Showtime drama Shameless.
More: Allison Janney, US TV
Related Stories
Tube Talk
'Bedlam': On set for the new seriesTube Talk takes a trip to the Bedlam set and speaks with star Lacey Turner.
US TV Interviews
'Mike and Molly' Reno Wilson Q&ADigital Spy chats to Reno Wilson about Mike and Molly's wedding and beyond.
US TV Ratings
'Duets' beats 'Touch' finale on ThursdayMeanwhile, CBS wins primetime with a lineup full of repeats.
2012-13 Season
'Sherlock's Lara Pulver joins new dramaLara Pulver will star in the new Starz series about Leonard Da Vinci.
