Kirk's family tells TMZ the actor died over the weekend. We're told he died from lung cancer ... and had only been diagnosed 6 months ago.

Early in his career, Kirk studied comedy at Groundlings and Second City. He got his start as a sound coordinator on the cult classic film "Killer Klowns from Outer Space" before getting acting roles, including "3 Ninjas: High Noon at Mega Mountain" and "The Sixth Man."

He also landed a number of guest roles on shows such as "Felicity," "Sisters," and "NYPD Blue." Recently, Kirk has worked primarily as a voice artist on a number of anime shows and video games, including "Cowboy Bebop," "Ghost in the Shell: Stand Alone Complex" and ".hack//."

Most notably, he played Kevin "Ug' Lee in Nickelodeon's "Salute Your Shorts" in 1991 and 1992.

In 2019, the cast had a reunion in Hollywood at the Good Burger pop-up shop. He remained close friends with most of the cast members and production staff.

He worked up until the last few months of his life, loving his career until the end.

Kirk was 59.