Trivia

Was mentored by actor Mark Ruffalo at the beginning of his career.

Has two children: daughter Nina Sadoski (Nina Seyfried Sadoski) (born March 21, 2017) and a son (born 2020) with wife Amanda Seyfried.

Nominated for the 2009 Tony Award for Best Performance for a Leading Actor in a Play for "Reasons to Be Pretty".

On November 29, 2016, Thomas and his then fiancee, Amanda Seyfried, announced they were expecting their first child in spring 2017; a few days later, during a different interview with W magazine, Amanda unintentionally revealed they were expecting a boy. The "W Magazine" interview appeared in the January 2017 issue. However, the revelation turned out to be incorrect, and when their first child was born on March 21, 2017, they named her Nina Sadoski (full name: Nina Seyfried Sadowski).

At Williamstown Theatre Festival, he was given the nickname "Lots o' lips".

His father is of one half Polish, one quarter Swedish, and one quarter English (with distant Welsh), ancestry. His mother is of half Italian and half German descent.