Shatner is best known for his roles on TV's "Star Trek" and "Boston Legal."
Tyler has worked on "Friends," "CSI" and "Ghost Whisperer."
The two are slated to appear on the update of the classic game show when it premieres Dec. 21 with Regis Philbin acting as host.
Contestants on the show will team up with celebrities in an effort to win up to $1 million.
"As the designated celebrity and contestant take turns being the clue-giver and clue-receiver, one-word hints are given to determine that round's 'password,'" CBS said in a news release. "If the player and the celebrity can work together to successfully give and receive clues in multiple rounds, the contestant may be able to guess the 'million dollar password' and win the cash that goes along with it."