Carroll was born in Manhattan, a bustling metropolis in the heart of New York City, and spent his formative years in Forest Hills, a predominantly Jewish community nestled in the borough of Queens. Upon graduating from high school in 1942, he joined the Merchant Marines, where he worked on ships traversing the Atlantic Ocean. Following his stint in the Merchant Marines, Carroll enrolled at the University of Montana in 1946 to pursue a degree in English, during which he developed a passion for theater. It was during one of the university's amateur productions that he met Nancy Fields, whom he would later marry in 1951.
After completing his studies at the University of Montana, Carroll relocated to Ireland, where he continued to hone his theatrical skills at the National University of Ireland. His talent was soon discovered, and he was assigned to appear at the renowned Dublin Gate Theater. Carroll went on to work in the theater scene in Europe until 1954, when he returned to New York City.
Despite his best efforts, Carroll's attempts to secure a spot on Broadway were initially unsuccessful, and he was forced to take on a teaching position until 1958, when he finally landed an Off-Broadway production, "Ulysses in Nighttown". He continued to make a name for himself in the theater world, working on a Broadway production directed by none other than Burgess Meredith, "God and Kate Murphy", in which he took on dual roles as both an understudy and an assistant stage manager.
Simultaneously, Carroll began to garner attention on television, landing a variety of character roles throughout the 1960s. A pilot for "Those Were The Days", based on the English hit "Till Death Us Do Part", was initially rejected by the networks in 1968 but was later re-cast and re-shot, eventually becoming the hit show "All in the Family" in 1971. The rest, as they say, is history.