Mr. Everdeen was Katniss's father. He died in a mine explosion when Katniss was very young.
Mr. Everdeen would often take Katniss to a special lake in the woods outside District 12 that had a small cabin beside it. He would sing her songs, and show her the Katniss roots at the bottom of the lake for which she was named after. He was also the man who first taught Katniss how to hunt. He often joked to Katniss that she'd never go hungry if she found herself.
After his death, Katniss continues to go hunting wearing his boots and leather jacket.