Thurl spent much of his time as a singer, with The Sportsmen, then after World War II, The Mellomen. That group in particular were very successful singing backup vocals with a host of stars from pop in the early to mid-1950's, Danny Kaye, Rosemary Clooney, Frank Sinatra and Elvis as well as a large number of ads for radio and television.
His deep base voice attracted attention all on it's own, and in 1952 he became the voice of Tony the Tiger for Kellogg's Sugar Frosted Flakes, a job he held up to his death in 2005.
Another voice that he provided (although uncredited at the time) was in the television rendition of, "How the Grinch Stole Christmas". It was accidentally left off the credits, but that bass voice has entertained millions with, "Your a Mean One, Mr. Grinch" in 1966.
He attempted a solo career during the mid/late 50's with a series of singles which covered varied styles. "Pay as I Go" was the B side of "Dr. Geek" (Of Tanganuika). He did quite of bit of work with Disney over the years, and it has some of that feel to it here.