11. My Long Lost Love Has Returned But Only I Can See Him Denny (Grey's Anatomy)
Surgeons are capable of many great things and those at Seattle Grace / Grey Sloan Memorial (or whatever the hospital is called these days) are some of the very best on television. It's what Grey's Anatomy really excels at; ground breaking surgeries and bizarre medical cases. The many angst-ridden relationships are just window dressing. However there is one thing even these doctors cannot do; bring a character back to life two years after he died. You'll be forgiven for thinking I'm talking about Supernatural, where ghostly resurrections are two a penny. But Jeffrey Dean Morgan wasn't playing Sam and Dean's father John Winchester in this case; he was Izzy's long lost love Denny, the man whose LVAD wire Izzy famously cut in order to save his life in season two, only for him to die anyway. Everything about his return in season four is frankly ridiculous. The impact of his death was ruined by bringing him back into the show. A hallucination caused by her metastatic melanoma, we witnessed week after week an intelligent, skilled surgeon ignoring her symptoms and having invisible sex in her room with a two-year dead / ghost lover instead. Denny's return wasn't a bittersweet reunion; it was a stupid, drawn out plot that took the show off the deep end. Thankfully with all that mess dealt with and Izzy's treatment underway, the show would get back to what it was good at.