( CNN ) -- Veteran actor Len Lesser died in his sleep Wednesday morning in Burbank , California , of complications from pneumonia . He was 88 . `` It was very peaceful , '' his daughter , Michele Lesser , told CNN , saying the family had hoped for a quick and painless death . `` He was a great grandpa , and an amazing father . He had a heart of gold -- and a sense of humor of platinum . '' Best known as Jerry Seinfeld 's Uncle Leo on TV 's `` Seinfeld , '' Lesser made more than 500 film , television and stage appearances . His TV roles ranged from `` Studio One in Hollywood '' in 1949 to a 2009 role on `` Castle . '' In addition to `` Seinfeld , '' he had a recurring role as Garvin on `` Everybody Loves Raymond . '' He also appeared on `` ER , '' `` Mad About You , '' `` Thirtysomething , '' `` Falcon Crest , '' `` Quincy M.E. , '' `` The Rockford Files , '' `` Kojak , '' `` The Bob Newhart Show , '' `` The Mod Squad , '' `` Green Acres , '' `` All In The Family , '' `` The Monkees , '' `` Get Smart , '' `` My Favorite Martian , '' `` Ben Casey '' and `` The Untouchables . '' Lesser 's films included `` Gallipoli , '' `` The Outlaw Josey Wales '' and `` Kelly 's Heroes . '' Lesser also served in the Army during World War II . In addition to his daughter Michelle , Lesser is survived by a son , David , David 's wife Julie and the couple 's three children .
Sol Lesser was a World War II veteran . He appeared in hundreds of television shows and movies .