Michael Shannon, who played General Zod in Man of Steel, was initially hesitant to return as the villain in The Flash until Zack Snyder gave his blessing.
The Flash's Michael Shannon Got Zack Snyder's Blessing to Return
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The Flash: Michael Shannon Says He Only Returned as Zod Because of
Michael Shannon Asked Zack Snyder For His Blessing Before
The Flash': Michael Shannon Got Zack Snyder's Blessing to Return as Zod
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Michael Shannon Got Zack Snyder's Blessing to Return as General
Like Somebody Playing With Action Figures: Michael Shannon Calls General Zod Role In The Flash Unsatisfying
Michael Shannon Got Zack Snyder's Blessing to Return as General
Michael Shannon On Zod's Return In The Flash Movie - IMDb
The Flash Star Michael Shannon Says Returning to General Zod 'Wasn
The Flash's Michael Shannon Got Zack Snyder's Blessing to Return
The Flash (film) - Wikipedia