Aaactually, I thought about it and I have a more fitting character idea. The one I previously mentioned is more for a fantasy setting-and I have one I've had stowed away for a superpower setting for a while now.
A character that has complete conscious control over his body at a subcellular level. That is, he can consciously alter his DNA, cellular make-up and speed of cellular regeneration. By extension this gives him greatly enhanced strength (not as much as someone with their main power, though; his is limited by what is biologically possible, unlike a pure 'super-strength' power), enhanced speed (again, not physics-defying), enhanced healing and healing speed and immune system, shapeshifting (I'll go into more detail in another paragraph) and enhanced digestion.
All of his abilities are really just different techniques given by his two actual basic abilities-the ability to alter his DNA and the ability to control his cellular regeneration and multiplication. By altering his cellular make-up and growing more cells at a faster rate, he can grow more strong cells (or faster, etc), he can effectively grow stronger or faster. By only increasing the speed of cellular regeneration/growing of new cells, he effectively heals faster; note, though, that cells growing at a faster rate is an effect and is part of the problem of cancer and increases the possibility of making a mistake in the genetic code copied (and the more complex the type of tissue, the more so), and he can only activate it consciously-thus meaning the faster he goes, the greater the chance he'll become sick/grow malformed tissue (he can easily remove it without any lasting effects; quite a problem in time-sensitive situations, though), and ESPECIALLY with organs (and he can't fix those as readily), meaning he can't heal organs as fast. As it is also conscious-only, he cannot heal from wounds while unconscious or survive outright mortal injuries like dedicated healers.
As for 'shapeshifting-this is limited mainly to gross mutations like strange appendages, looking like other humans or growing natural weapons. While, technically, he can (in theory) shapeshift into any biological matter, it will actually turn him into that-meaning that, were he to turn into a dog, for example, he would have the intelligence of a dog and not be intelligent enough (or perhaps even remember being) to return to his natural form.
The last part-digestion-is important as he has to spend the physical energy to grow as normal-which means eating A LOT to be able to do what he does, often as he's doing it. Growing flesh takes a lot of matter and energy. Unfortunately, especially in combat-and as using this power seems to tap into the most savage 'do-or-die' part of his mind, and considering the specific nutrients needed, this can mean other humans make a near-perfect (and available) source. Think Carnage from Spider-Man (or a very toned-down Alex Mercer from Prototype).