No, Theodore is not a biblical name. It is of Greek origin and means "gift of God," but it does not appear in The Bible as a person's name.
Theodore Roosevelt did not have a middle name. His full name was simply Theodore Roosevelt.
Theodore Beale's birth name is Theodore Beale.
Brother Theodore's birth name is Gottlieb, Theodore.
Theodore Mann's birth name is Theodore Goldman.
Theodore Sorensen's birth name is Theodore Chaikin Sorensen.
Theodore Shapiro's birth name is Theodore Michael Shapiro.
Theodore Roosevelt's birth name is Theodore Roosevelt Jr..
Theodore Dreiser's birth name is Herman Theodore Dreiser.
Theodore Case's birth name is Theodore Willard Case.
Theodore Zichy's birth name is Theodore Bela Zichy.
Theodore Pratt's birth name is Theodore George Pratt.
Theodore Henderson's birth name is Haines Theodore Henderson.