Kirschenbaum, who co-created TV sitcoms Yes, Dear and Friend Me, was 51 years old at the time of his Friday (26Oct12) death, which was first reported by Deadline.com.
The comedy writer and producer worked on a number of hit shows during his career, including My Name Is Earl, Raising Hope, Coach, and Baby Talk.
A host of Hollywood stars have taken to Twitter.com to remember their former colleague, with Pressly writing, "Today my heart is heavy and saddened by the death of an incredible human being, Alan Kirschenbaum."
She adds, "I had the pleasure of workin w (with) him on Earl... Alan was 1 (one) of the funniest, kindest, most endearing writers n (and) people I have ever had the honor of knowing and workin w. My heart goes out to his wife Vicki and daughter Molly in this terrible time of loss. Everyone who was ever graced by his presence is heart broken and shocked. He will never be forgotten and will always be 1 of the greatest comedy writers ever. Rest in peace my friend."
Her former Earl co-star Ethan Suplee offers, "RIP, Alan Kirschenbaum, I was always happier in his presence and was devastated to hear of his passing," while Elfman tweets, "Very, very sad. worked w/ him in 2009. Very kind, sweet man."
Sex And The City star Willie Garson writes, "R.I.P. Alan Kirschenbaum... Excellent person, fantastic writer, completely shocked and devastated... a VERY bad day."
O'Malley, who had a lead role in Kirschenbaum's Yes, Dear, tells Deadline, "Alan Kirschenbaum was an amazing boss, colleague and friend. Funny, funny man with a huge heart. Beloved by countless friends - and now missed by them all. Rest in peace."