24. January Jones
Worst Performances: Unknown (2011), X-Men: First Class (2011)
Fact: January Jones should stick to television.
On AMC's Mad Men, her cold, steely demeanor fits the character of Betty Draper perfectly, since the ex-wife of Jon Hamm's Don is, by all accounts, an ice queen. But whenever Jones steps off the period drama's set and dabbles in moviemaking, her frozen charisma downgrades otherwise solid films. Case in point: Last year's superhero knockout X-Men: First Class, in which Jones' performance as the villainous Emma Frost is more the work of a costumed mannequin than a professionally trained actress.