Yahootvblog.com reports Len Lesser, best known as Jerry's Uncle Leo on the long running sit com  "Seinfeld" has passed away.

  Lesser — who uttered his famous "Hello!" dozens of times as Jerry's Uncle Leo on the long-running sitcom "Seinfeld" — died of cancer-related pneumonia at the age of 88; he is survived by two children.

 Lesser started his career in the earliest days of television, with a role on "Studio One in Hollywood" back in 1949. From there, he racked up appearances in classic TV series, from "Dragnet" to "Alfred Hitchcock Presents" to "Gunsmoke," among many others. Here's a look at Lesser in a 1985 episode of "Airwolf," playing against Uncle Leo type as an Old West villain in a theme-park stunt show.