Though he has a rough past, Sam grew up to be a kind person. He's responsible, compassionate and generous. He's as loyal as a dog. He is a protective person who likes to keep an eye on those he cares about, though he does his best not to seem over-bearing. His friendly and easygoing nature helps him get along with nearly everyone. Despite his kindness and thoughtful nature, he does have anger management problems, which seem to be common among Shifters. His temper issues grow more volatile as the show progresses, but he's recently been managing to mellow out despite all the emotional trauma he's been facing.
In his early 30's, he is of average height and strong build, with gray eyes and shaggy brown hair, much in line with his alternate form. While he can change into any animal (so long as there is a suitable 'template' animal around for him to use as a basis), Sam's preferred alternate shape is that of a light-colored border collie.
Like all shapeshifters, Sam feels a strong urge to change shape on the nights of a full moon. The rest of the time he can do so at will. He often will go for runs in dog form through the local woods with his canine friends.
Although not usually an angry person, Sam has shown that he has a bad temper, shown to even be capable of killing. ("I Smell a Rat") He appears to dislike vampires, and has an even deeper hatred for werewolves and werepanthers; he nearly beats Calvin Norris to death in Season 3 and when Sookie compares him to a werewolf, he resents the thought.