Even when discussing his brash comedic style, Don Rickles couldn’t help himself. “Every night when I go out on stage, there’s always one nagging fear in the back of my mind,” he once explained. “I’m always afraid that somewhere out there, there is one person in the audience that I’m not going to offend.”

Fortunately for the man universally and ironically known as “Mr Warmth”, Rickles offended plenty of audience members throughout a landmark and unmatched career in American comedy, endearing him to generations of fans. The legendary comic’s death at 90 marks the arguable end of an era dominated by old-school comedians with a passion for both the silly and the crass, with Rickles one of the last surviving – and performing – marquee names of 60s and 70s Rat Pack-era show business.

In fact, it was Rickles’ longevity in entertainment that made him such a celebrated anomaly later in life. Born in Queens in 1926, he tried out an acting career after a stint in the navy during the second world war. He then transitioned to standup comedy, where he eventually gained a reputation for combatting hecklers with insulting barbs. It was in countless late nights on stage at smoke-filled clubs around the country that Rickles developed his comedic voice, essentially an inner monologue of mischievous thoughts one would only wish to have the courage to say out loud.

After becoming a staple in Vegas and finding a friend in the superstar Frank Sinatra (whom Rickles famously loved to rib), he broke on to the national scene after a 1965 appearance on The Tonight Show Starring Johnny Carson. Remarkably, Rickles managed to maintain relevance ever since, with a busy performance schedule that saw him alongside everyone from Sinatra in his heyday to, more recently, regular outings with his friend Regis Philbin. His filmography is also a genre-spanning and impressive laundry list of hits, ranging from his roles in the Martin Scorsese-directed mob opus Casino to the animated Toy Story series, in which he gave life to Mr Potato Head, a character that made his voice instantly recognizable to a generation of children even if his face wasn’t.

Throughout the past decade, Rickles enjoyed legendary status, with a penchant for befriending newer generations of stars such as Howard Stern, Jimmy Fallon, and Jimmy Kimmel, frequently making appearances on the trio’s respective shows. The subject of the 2007 documentary Mr Warmth: The Don Rickles Project, the comedian also maintained a presence on Twitter, an accomplishment for any 90-year-old, no less one who sporadically would tweet out trademark wisecracks. (“Healthy & happy New Year to all my family, friends and followers, and to all service men and women,” he recently posted. “Please stay safe & remember to duck!”)

His targets would typically wear these wisecracks – some innocent, others not so much – as a badge of honor, whether the victims were randomly chosen members of his audience, or names as well-known as his – as when he tweeted about having “the honor of being with Nancy Reagan” at her husband’s second inaugural (a gig he would later call his favorite ever). “I ribbed her and she laughed wholeheartedly.”

Even Sinatra, famous for his poise and no-nonsense attitude, relished the opportunity of being poked at by Rickles, a friendship on full display in a story both Sinatra and Rickles loved to tell. “He came over to the table and he said: ‘Frank, do me a favor, will you?’” Sinatra once explained. “‘I’m sitting with a very pretty girl and, uh, I’m trying to make out, you know. I told her I know you and she really doesn’t believe me. Would you stop by the table?’ And I said all right, I was just about finished, and I walked by the table and I said, ‘How are ya, Don? Nice to see you.’ And he said, ‘Can’t you see I’m eating, Frank?!’”

Rickles’ impact on the world of comedy will continue to ricochet throughout the artform, whether on stage, film or television, from his influence on Comedy Central’s famed roasts to his forthcoming turn in the latest installment of the Toy Story series, set to hit theaters in 2019. Unfortunately for him, however, countless luminaries are currently giving heaps of something that would probably make the legend cringe: praise. “A God died today,” tweeted Tom Hanks. “Don Rickles, we did not want to ever lose you. Never.” Elsewhere on Twitter, Jim Carrey echoed those sentiments, calling him a “comic Everest” and recalling: “Don once begged me for a couple of bucks then told me to twist myself into a pretzel. Ego slayer!” His friend Jimmy Kimmel, meanwhile, said it simply: “90 years with Don Rickles weren’t enough. One of the sweetest and most lovely people I had the pleasure of knowing. We miss you already.”