Robert John Gsellman
- Bats Right, Throws Right
- Height 6' 4", Weight 205 lb.
- High School Westchester High School (Los Angeles)
- Debut August 23, 2016
Pitcher Robert Gsellman was credited with the win in his major league debut with the New York Mets on August 23, 2016. He had to relieve starter Jon Niese in the 1st inning when Niese left with an injury after one out, and he pitched 3 2/3 scoreless innings to receive credit for a 7-4 win over the St. Louis Cardinals.
Through 2019, he is the only major leaguer whose last name starts "Gs".