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Inspired by this question, I'm wondering if Voldemort can cast a Patronus.
It seems to be a basic spell of protection which he would have needed to have at some point (with all of the dark things he sought out and dealt with) and yet he had split his soul many times which might effect his ability to make one.
Voldemort doesn't understand the power of love, and as well as this I don't think he understands happiness. He fought against the world to make it his, to win and succeed. He never wanted to be content, and only took joy in dark terrible things.
We know this from one of Dumbledore's descriptions of Voldemort
Your mother died to save you. If there is one thing Voldemort cannot understand, it is love. He didn't realize that love as powerful as your mother's for you leaves its own mark.
If he is unable to realise how love was an ingredient in powerful magic, how could he understand the use of happiness either? He would have defended himself by force.
A second point: Like Snape, Voldemort grew up a very unhappy child, and from what I remember did not find happiness at Hogwarts either, merely satisfaction and justification of his thoughts and beliefs, that he was different but only because he was better than others. That's not happiness.
‘With an incantation, which will work only if you are concentrating, with all your might, on a single, very happy memory.’ Love wouldn't seem to be a component of the Patronus charm, and happiness can mean different things to different people. Also, the Patronus charm likely was not as obscure a magic as the protective charm Lily placed on Harry with her sacrifice, so assuming Voldemort wouldn't know about is may be reaching a bit.
JKR noted in a webchat that Snape was the only Death Eater capable of creating a Patronus and only then because he wasn't really in league with them (e.g. due to his love for Lily Potter)
Samantha: Was Snape the only Death Eater who could produce a full patronus?
J.K. Rowling: Yes, because a Patronus is used against things that the Death Eaters generally generate, or fight alongside. They would not need Patronuses.
In the "Wonderbook : Book of Spells", we see a dark wizard by the name of Raczidian attempt the Patronus and learn the consequences should a "competent but unworthy wizard or witch attempt the spell", namely that you're covered by maggots which engulf your flesh (ouch)
There's been some caveating on Pottermore, regarding the ability of some of Voldemort's hanger's-on (i.e. Umbridge) being able to use a Patronus. In short it's because they're lacking a capacity for introspection...
The Patronus Charm is one of the most ancient of charms and appears in many accounts of early magic.
In spite of a long association with those fighting for lofty or noble causes (those able to produce corporeal Patronuses were often elected to high office within the Wizengamot and Ministry of Magic), the Patronus is not unknown among Dark wizards. While there is a widespread and justified belief that a wizard who is not pure of heart cannot produce a successful Patronus (the most famous example of the spell backfiring is that of the Dark wizard Raczidian, who was devoured by maggots), a rare few witches and wizards of questionable morals have succeeded in producing the Charm (Dolores Umbridge, for example, is able to conjure a cat Patronus to protect herself from Dementors).
It may be that a true and confident belief in the rightness of one's actions can supply the necessary happiness. However, most such men and women, who become desensitised to the effects of the Dark creatures with whom they may ally themselves, regard the Patronus as an unnecessary spell to have in their arsenal.
Voldemort would certainly fall into the latter category. Not only would he consider the spell largely pointless (not to mention unnecessarily risky) but it's unlikely he could summon a 'pure talisman memory' that would satisfy the requirements of the spell given that his soul was so dramatically splintered and corrupted by the various murders he'd committed in the creation of his various Horcruxes.
The Harry Potter Wikia has this story of the dark wizard Raczidian:
Enraged that something so small should thwart him, Raczidian decided to enter the fray himself, and attempted to summon a Patronus to ward off Illyius's mouse. However, he failed to remember that only the pure of heart can produce a Patronus, and thus for the first time in history, it was revealed what happens when a competent but unworthy wizard or witch attempts the spell. Maggots shot out of Raczidian's wand and quickly devoured him as they engulfed his body.
If we consider that Voldemort is an even more evil wizard we can assume that a Patronus by him could fail even more than the one from Raczidian.
The source for the story of Razcidian and his failed Patronus spell is the Playstation 3 video game/augmented reality book "Wonderbook: Book of Spells" which is part of Pottermore.
Pottermore is based on cooperation between J. K. Rowling and Sony has worked on this game, so it could be considered canon. For a further discussion of canon and Pottermore see this meta question.
(PS: This answer is inspired by this comment by N Unnikrishnan.)
