Rancho Nicasio is raising funds for its lead bartender as he undergoes treatment for a type of non-Hodgkin’s lymphoma. Nasso Nicolaou, a towering presence at the bar for the past 18 years, has been unable to work since January, after being diagnosed with diffuse large B-cell lymphoma. A GoFundMe campaign raising money for his medical expenses has so far brought in $23,912. “This funding has taken a lot of pressure off of the family,” Rancho owner Bob Brown wrote in an update last week, adding that he has four “grueling months of chemo treatments in front of him. So let’s keep this thing going for a while.” Mr. Nicolaou is known not just for his bartending skills—friend Harris Wolfson said he makes the best mandarin cosmopolitan, according to his wife—but also as an artist. “He’s kind of shy about his work, but then sometimes he kind of isn’t,” Mr. Wolfson said. Mr. Nicolaou’s modernist paintings tend to be pretty big, and Mr. Wolfson said he once suggested he try more modest pieces that normal walls could accommodate—beginning with a self-portrait that he commissioned. (The painting is somewhat abstract, with a blue-black background and a seafoam green form suggesting the outline of a nose and a winking eye, along with the words in Greek for “free spirit”—a nod to his Greek heritage.) In addition to painting and bartending, Mr. Nicolaou also enjoys swimming in Tomales Bay. “He’s been an avid swimmer for many years,” Inverness resident Thackary Grossman, a fellow swimmer, said, noting that he would often sprint long distances, then return, rest and go out again into the water. “He would often be the last of the swimmers to go out.” To donate to his campaign, visit gofundme.com/a-cancer-fund-raiser-for-nasso.