Frederick Dalton Thompson served as a U.S. senator from Tennessee from Dec. 2, 1994, to Jan. 3, 2003. But you probably know him as actor Fred Thompson, who portrays Arthur Branch, the authoritative D.A. who leads with a quip and an iron fist on "Law & Order."

Fred Thompson is expected to announce tomorrow that he will seek the Republican nomination for president.

Now there's a chance you'll know him as "Mr. President."

The 65-year-old actor-turned-politician-turned-actor takes another turn tomorrow, when he officially announces that he's a candidate for the presidency. His intentions will probably be on the agenda tonight, when Thompson appears on "The Tonight Show With Jay Leno." (Starting Saturday, NBC will no longer run "Law & Order" episodes with Thompson's character because of concerns over federal equal-time provisions, but TNT will continue to air those and other "L&O" reruns.)

Thompson follows fellow Republican Ronald Reagan to the campaign trail, which Reagan successfully navigated for a two-term presidency in the 1980s.

Here are a few other relatively recent examples of American actors who have won the hearts and votes of the public:

In California, where Hollywood is a statewide theme, the Governator, Arnold Schwarzenegger, wrested the job from Gray Davis in 2003. (When Schwarzenegger first ran for governor, Sci Fi and FX stopped showing his movies because of equal-time worries).

Other high-profile elected officials in California have included Clint Eastwood as mayor of Carmel and the late Sonny Bono as mayor of Palm Springs. Sheila James Kuehl -- who played Zelda Gilroy on TV's "The Many Loves of Dobie Gillis (1959-63) -- currently represents the 23rd District in the state senate.

Jesse Ventura's "Body" of work was mostly as a pro wrestler before he was elected the 38th governor of Minnesota. He served from 1999 to 2003 without seeking a second term.

Fred Grandy -- who stumbled across "The Love Boat" as Gopher for nine years -- became a member of the U.S. House of Representatives from his native Iowa in 1986.