Don Surber links to an item that Martha Logan somehow resembles Hillary Clinton. I think that there's a more obvious parallel.
Read more at risk of "24" spoilers.
The one character in "24" who most resembled Hillary was Sherry Palmer. (I credit my wife for this observation.) Sherry Palmer is the manipulative wife of Senator (later President) David Palmer. On the first day, her persona changes from loving, supportive wife to schemer, interested in riding into Washington on her husband's coattails. Though she didn't use the phrase you could hear her saying that electing her husband would give Americans "two for the price of one."
If there's one difference between Sherry Palmer and Hillary Clinton it's that Sen. Clinton forgave her husband's philandering in order to keep climbing to the top; Sherry Palmer (unsuccessfully) encouraged her husband to stray in order to reach the White House. Another difference is that Hillary Clinton reached the White House once (at least) while Sherry Palmer never quite got there.
The naked ambition of Sherry Palmer is obviously an exaggeration. Perhaps it's not as obvious who she's based on. Clearly the Sherry/Hillary similarities are not as obvious as the Logan/Nixon ones. But I think that the creators of "24" may well have had Hillary Clinton in mind when they created Sherry Palmer.
24,
sherry palmer,
hillary clinton.