Seinfeld's 'Uncle Leo' dead at 88

Actor Les Lesser, perhaps best known for his role as Uncle Leo on Seinfeld, has died of cancer related pneumonia at a care facility in Burbank, Calif

"Jerry! Hello!" was his slogan and he used it to steal every scene he was in.

If you didn't know Lesser from Seinfeld you likely still recognize his face. He started acting in 1954 and appeared in the movies Birdman of Alcatraz, Kelly's Heroes, Papillon and Clint Eastwood's The Outlaw Josey Wales."

You also might have caught him performing on televisions Get Smart, The Munsters, The Rockford Files, ER and Everybody Loves Raymond.

Lesser was a great character actor because he was a great character and a great actor. he will be missed by millions of fans.

Fittingly, both "Len Lesser" and "Uncle Leo" are Trending Topics on Twitter:

@odainai O Uncle Leo do Seinfeld morreu :( RIP Len Lesser

@kevincorey GOODBYEEEEE Uncle Leo....:(

@drmcbride RIP Uncle Leo from Seinfeld.

@NokoVT RIP Uncle Leo. You'll be missed.

@michaelombardi Sad day for all us Seinfeld fans, Uncle Leo has passed away--Len Lesser who played Leo died at 88 http://tiny.cc/ok5w8

@HempStevens On a sad note, Len Lesser, the actor known as "Uncle Leo" on Seinfeld has passed away ... Thanks for all the... http://fb.me/KPpdXMay

@BentRazor Heeeeellllllllllooooooooooooo Jerry. R.I.P. Uncle Leo.

@mynamerhymez Happy Birthday to Michael Jordan, and RIP to "Uncle Leo" #CircleofLife #Seinfeld

@blancaeruiz Seinfeld's uncle Leo died. Jerry must be sad he didn't spend more time with him.

@talldrinkh2o Uncle Leo... you will live on forever. http://ow.ly/3Ydme #seinfeld

@darkdriving At first I just thought it was weird that so many people all had an Uncle Leo that died. Then my brain started working and I figured it out.

@KatherineBull Aww..he was my favorite. Len Lesser, Seinfeld's Uncle Leo, Dies : People.com http://goo.gl/w1pjh

@brianmoranjr Uncle Leo! Hellooo! Now Goodbye. #RIP #UncleLeo

@Bianca431 RIP "Uncle Leo" (Len Lesser) You were one funny guy.

@gutogattuso Aff, da voltando de ver Seinfeld o dia inteiro pra relembrar uncle Leo =(