Mark’s 21-year battle with prostate cancer ended peacefully on Sunday, May 17, 2026. Mark was born in Michigan and grew up in the deserts of Arizona and Southern California along with his five siblings. Mark’s career in software development spanned many companies and titles, and also brought Mark to Seattle where he met his wife, Jessica, working at a startup together in the late nineties. They bonded over their shared love of Guinness.

Fiercely independent and athletic, Mark was an avid surfer and cyclist. You could often find him along the coast in San Diego or Mexico, checking out the quality of the waves in the early morning light. He loved cycling – both the actual riding and watching professional races. In fact, he once owned more than 20 bikes, many of which he built himself. In 1999 Mark and Jessica went to France and followed many stages of the Tour de France. Logan still has the t-shirt Mark got thrown to him at la Caravane publicitaire.

Back home, Mark completed the Seattle to Portland (STP) bike ride multiple times and eventually created his own ride he called the “STS” (Seattle to Seattle) so he didn’t have to deal with the hassle of bussing back. When Logan was little, he expressed interest in skiing so Mark went all in like always. He took Logan up to Snoqualmie Pass for a weekend and got him a private lesson. After that, Mark was obsessed, and you could find him and Logan bombing down Silver Fir as often as possible in the winter.

Mark could fix almost anything and would create tools to solve all sorts of problems. He earned the nickname “handy husband” tenfold. He was always keeping the yard trimmed and tidy and the garage is a masterpiece of organization with everything in its place.

Mark played guitar and wrote many songs at the end of his life including an ode to Logan titled, “Father Says.” Mark was a stoic, insular person so if you got to experience his quiet, and oftentimes hilarious, dry humor you knew you were one of the lucky ones. Mark was a wonderful dad, and a supportive partner, brother, friend and son.

He fought a long and hard battle with his disease, undergoing countless treatments and clinical trials to be here for his family. He was incredibly strong and stayed active until this year. Amazingly, he even biked to some of his treatment appointments. He will be sorely missed by many.

Mark is preceded in death by his parents Mary Jane and John Plesko, his eldest brother Jack Plesko, and his dog Shadow. He is survived by his wife Jessica and son Logan, as well as his sister Alexis and husband Joe Gonzalez, sister Amy Cooper, brother Matt Plesko and wife Diane, sister Tess Murphy and husband Kevin, in-laws Marcia and Michael Horswill, many nieces and nephews, and his dog Cori. Celebrations of Mark’s life will take place in Seattle and later in California – dates and locations to be determined. In lieu of flowers, the family requests you to consider a donation to Fred Hutchinson Cancer Research Center.