Star Trek's Captain Kirk, William Shatner is the only living man known to have a symbiotic relationship with a fluffy hamster. The hamster has been embedded into the skin of its scalp, where it functions as a hairpiece.
Rumors that the hamster is, in fact, an alien overlord have never been proven.
Some observers suspect that Peter MacNicol may have developed hamster symbiosis, but this is likewise unproven.
..."O.K., let's see, Shatner, Shatner... no, it doesn't look like he's in this one. We're safe."
..."Wait, aaughh! My eyes, my brain, my soul, my everything! Hurrrrts!"