Sam Heughan Shares a Sweet Birthday Message for 'Outlander' Co-Star Caitriona Balfe!

Sam Heughan is thinking of Caitriona Balfe on her special day.

The 40-year-old actor shared a sweet message for his now 41-year-old Outlander co-star on Sunday (October 4).

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“Wishing my wonderful friend + brilliant costar @caitrionambalfe HAPPY BIRTHDAY! Strong, intelligent, passionate woman who stands for equality and democracy. Love u loads. Please join me, donate to @onetreeplanted TY to the wonderful fans who set this up!” he wrote, along with a link to a fan-created fundraiser.

Earlier in the year, Caitriona joked about what she got Sam for his birthday.