Nicholas Alan "Nick" Gehlfuss (born January 21, 1985) is an American actor. He is known as Robbie Pratt in the fourth season of the Showtime comedy-drama Shameless. Since 2015, Gehlfuss has portrayed Dr. Will Halstead in Chicago Med, Chicago Fire and Chicago P.D.
Gehlfuss was born in Cleveland, Ohio and raised in Little Italy. He holds a Bachelor of Fine Arts from Marietta College and completed his Master of Fine Arts at University of Missouri-Kansas City. On May 13, 2016, Gehlfuss married hotel marketer Lilian Matsuda.
In 2014, Gehlfuss had a recurring role as Robbie Pratt in the fourth season of the Showtime comedy-drama Shameless. In 2015, he guest-starred in the penultimate episode of the short-lived NBC horror drama Constantine. Later that year, Gehlfuss was cast in the NBC medical drama Chicago Med as Dr. Will Halstead. Halstead was first introduced in the police procedural drama Chicago P.D. as Jay Halstead brother and afterwards, the drama Chicago Fire's backdoor pilot for Chicago Med.