So far, no cause of death or further details have been public regarding Becker's passing.
Becker missed Steely Dan's Classic East and Classic West festival gigs in NY and Los Angeles in July because he was recovering from an undisclosed illness.
Steely Dan's songs were the "soundtrack to a lotta good times", tweeted Joe Scarborough, guitarist and host of MSNBC's "Morning Joe". Fagen told Billboard that he was recovering from a procedure but did not elaborate on what type of surgery.
The Steely Dan sound featured an original, sophisticated style of music that borrowed elements from rock, jazz, pop and soul. "He was cynical about human nature, including his own, and hysterically amusing".
Wrote Judd Apatow: "have played no band more often or enjoyed any music more than Steely Dan".
A few Steely Dan hits - "Show Biz Kids", "Rikki Don't Lose That Number", "Do It Again" - made uncredited appearances in low-profile, now-forgotten productions, but it was band's "FM (No Static at All)" that cemented its soundtrack bona fides.
Walter Becker performs with Steely Dan at the Beacon Theatre in New York City
The group split up in 1981 but reformed in 1993, and Becker also had a career as a solo artist. Fagen said in a statement that he intends to continue to perform Steely Dan's music with other musicians.
"His habits got the best of him by the end of the seventies, and we lost touch for a while".
Musicians were quick to mourn Becker on social media Sunday.
Both Ryan Adams and the band The Mountain Goats tweeted that Becker changed their lives. "Their 2000 album "Two Against Nature" collected four Grammys, including one for album of the year", Daily Variety reported. He and Fagen then reunited as Steely Dan and did their first tour in 19 years.
Becker and Fagen were inducted into the Rock & Roll Hall Of Fame a year later.More news: HOW TO MAKE AN AUTOMATIC FEEDER FOR BIRDS
More news: RITUALS OR CULTOS
More news: Converse outlet | Tumblr