Characters who did not appear on camera, but spoke from other rooms or announced on television, radio or answering machines.
Carol Ann Susi as Mrs. Wolowitz (Voice Only) (2007-2014) Howard's never seen over-bearing mother
Pamela Adlon as Halley; Howard and Bernadette's first child who sounds like Howard's mother when she cries.
Kimberly Brooks as Automated Cell Phone (Voice Only) The Dumpling Paradox from Howard and Christy's phone message. Also a computer voice in The Gyroscopic Collapse.
Jennifer Hale as News Announcer (Voice Only) The Lizard-Spock Expansion who announced the Mars Rover problem.
Robert Clotworthy as Announcer (Voice Only) The Lizard-Spock Expansion who announced the discovery of life on Mars.
Robert Clotworthy as Train Conductor (Voice Only) The Terminator Decoupling who provided the train announcements.
Robert Clotworthy as Astronaut (Voice Only) The Classified Materials Turbulence who quickly exited the International Space Station.
Travis Davis as Ground Controller (Voice Only) The Classified Materials Turbulence who was informed of the astronauts hasty exit.
Edward Lieberman as Announcer (Voice Only) The Staircase Implementation.
Edward Lieberman as Announcer (Voice Only) The Love Car Displacement.
Robert Clotworthy as Dave Roeger (Voice Only) The Launch Acceleration who calls Howard about his space flight.
Karl T. Wright as Jimmy (Voice Only) The Launch Acceleration who tells Howard that is space flight has been cancelled.
Endre Hules as Russian Mission Control (Voice Only) The Countdown Reflection for Howard's launch into space.
Rick Gifford as Guy (Voice Only) The Bakersfield Expedition.
Gilda Stratton as Flight Attendant (Voice Only) The Friendship Turbulence on Howard and Sheldon's flight to Houston.
Phyllis Timbes as Voicemail (Voice Only) The Relationship Diremption.
Michael Araujo as Stadium Announcer (Voice Only) The First Pitch Insufficiency at the California Angels' stadium.
Annie O'Donnell as Mrs. Lorvis (Voice Only) The Misinterpretation Agitation heard from hos geek basement sanctuary.
Mark Barrett as Guard #2 (Voice Only) The Skywalker Incursion at Skywalker Ranch.
Max Mittelman as Tech Support (Voice Only) The Graduation Transmission for the drone repair help line.
Katherine Von Till as Tech Support Recording (Voice Only) The Graduation Transmission for the drone repair help line.
Louise Claps as the Receptionist (Voice Only) The Matrimonial Momentum at the Las Vegas wedding chapel.
Jim Meskimen as Doctor/Man/Actor The Troll Manifestation heard on television from Penny's "Serial Apist 2" movie soundtrack.