The Best Guest Star of 2011 as voted by you the fans was.. Michael Rosenbaum - Smallville.
 
In the last season of the epic CW hit series Smallville, they brought in a plethora of guest stars from the past seasons to go out with a bang & to boost ratings. None were more prominent & anticipated than the return of Clark Kent's nemesis for several seasons, Lex Luthor, played by Michael Rosenbaum. Rosenbaum returned to the show that boosted his career for 1 final episode, the epic series finale.

Michael beat out another Smallville baddie, "Zod" actor Callum Blue finished 2, ahead of a plethora of Supernatural guest stars. James Marsters 3rd, Genevieve Padalecki 4th, Julian Richings 5th & Alona Tal in 6th. Perhaps too many choices for SPN fans prevented them from fighting for 1st. In 7th was Leverage guest star Mark Sheppard, 8th was How I Met Your Mother guest star Katie Holmes, 9th went to Community guest star Michelle Krusiec, and rounding out the finalists was Jennifer Love Hewitt from Hot In Cleveland.

Final vote totals.
Michael Rosenbaum "Smallville" 833
Callum Blue "Smallville" 749
James Marsters "Supernatural" 611
Genevieve Padalecki "Supernatural" 575
Julian Richings "Supernatural" 476
Alona Tal "Supernatural" 456
Mark Sheppard "Leverage" 298
Katie Holmes "How I Met Your Mother" 195
Michelle Krusiec "Community" 184
Jennifer Love Hewitt "Hot In Cleveland" 181