"I just felt the kind of stuff I do doesn't win awards. I didn't want to go through the process, the disappointment," he said.
In addition to Newhart, other winners for guest turns included Melissa Leo for the sitcom "Louie" and, on the drama series side, Dan Bucatinsky for "Scandal" and Carrie Preston for "The Good Wife."
With eight statuettes, HBO's Liberace biopic "Behind the Candelabra" was the night's top-winning individual program at the ceremony honoring technical and other achievements. The movie will compete for seven more nominations at next Sunday's Primetime Emmy Awards.
Heidi Klum and Tim Gunn of "Project Runway" won for outstanding host for a reality or reality-competition show, and "Undercover Boss" for outstanding reality program
Lily Tomlin received the trophy for best voice-over performance for her narration of "An Apology to Elephants," a documentary about the treatment of captive elephants.
Netflix's "House of Cards," the first online program to compete for top drama series honors, picked up trophies Sunday for casting and for cinematography for a single-camera series.
HBO earned a leading 20 awards, followed by CBS with 15 and NBC with eight.
Neil Patrick Harris will host next Sunday's ceremony airing on CBS.
Other winners at the creative arts Emmys included:
Commercial: "Inspired," Canon.
Animated Program: "South Park: Raising the Bar," Comedy Central.
Nonfiction series: "American Masters," PBS.
Children's Program: "Nick News with Linda Ellerbee: Forgotten But Not Gone: Kids, HIV & AIDS," Nickelodeon.
Music composition for a series (original dramatic score): "Downton Abbey: Episode 6," PBS.
Music composition for a miniseries, movie or special: "World Without End: Medieval Life and Death," ReelzChannel.
Casting for a miniseries, movie or a special: "Behind The Candelabra," HBO.
Casting for a comedy series: "30 Rock," NBC.
Costumes for a miniseries, movie or a special: "Behind The Candelabra," HBO.
Costumes for a variety-music program or a special (more than one award possible): "The 55th Annual Grammy Awards," CBS.
Costumes for a series: "The Borgias: The Gunpowder Plot," Showtime.
Stunt coordination for a comedy series or variety program: "Supah Ninjas," Nickelodeon.
Stunt coordination for a drama series, miniseries or movie: "Revolution: Nobody's Fault But Mine," NBC.
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AP Television Writer Lynn Elber contributed to this report.