Wyatt is often showed at two different ages in Charmed, therefore he's played by 3 actors. The twins Jason & Kristopher Simmons share the role of Wyatt at the age of 3; the actor Wes Ramsey plays Wyatt at the age of 25 and has been on 4 episodes as opposed to the twins, who are shown on almost every Charmed episode.
Wyatt Matthew Halliwell was born on February 2nd, 2003, the day of the Wiccan Festival of Lights, as the son of Piper Halliwell, a Charmed One, and Leo Wyatt, a Whitelighter. He is also the nephew of Paige Matthews, Phoebe Halliwell, and Prudence Halliwell (deceased), the older brother of Christopher Perry Halliwell and Melinda Halliwell, the grandson of Patricia Halliwell and Victor Bennet, and great-grandson of Penelope Johnson Halliwell. Wyatt's Whitelighter powers include healing, and sensing. His witch powers include conjuring, force field generation, thought projection, and telekinetic orbing. In years to come, his powers later grow to strangulation, energy waves, and energy ball projecting.
He was part of an ancient prophecy telling about the birth of a special, 'twice-blessed child' on the day when three planets would align, during a Wiccan sabbat, during the Aurora Borealis where all magic everywhere would cease to exist for one day. Wyatt had become this twice blessed child, and along with that, one of the most powerful magical beings ever to walk the Earth. As soon as evil found out about this pregnancy and about the power the child was deemed to possess, a plot was formed to steal the magical child from his parents: Piper Halliwell and Leo Wyatt. They planned to raise Wyatt as a powerful force for evil. Fortunately, the Halliwell Sisters were able to prevent this from happening. Although Piper and Leo already knew before birth, that their child was going to be very powerful, they hadn't expected him to be so powerful (nor that he was going to be a boy). The reaction of evil upon their child shocked them and it made them realize Wyatt would need to be carefully protected.
When two demons (Hawker Demon and a mercenary demon) try to steal the newborn baby for a high reward , Piper is outraged. She and Phoebe go to the Demonic Market where Piper vanquishes over half of all the demons in anger. Piper is very surprised when the Crone, a prophetic demon, announces that a law will be passed forbidding any further attempts on the child, considering that for evil, the costs of war will far outweigh the benefits. Eventually, the Crone herself tries to steal the child to see his future. However, regardless of all traps and spells, the sisters manage to vanquish the Crone and save Wyatt, but not before the Crone exclaims, "I've seen it all, such power - such power!"
Although his name breaks the Halliwell tradition of having a first name starting with "P", his surname is kept as Halliwell. According to Leo, "It's definitely Halliwell. Demons fear it, good magic respects it." Piper broke the family tradition of "P" names and gave her son the name Wyatt in honor of his father. His middle name becomes Matthew, in honor of Paige. While he was in the womb of Piper, he was still able to do magic. He could heal his mother's wounds and protected her and himself with a force field and the power of deflection. He knew how to control his mother's powers, and transformed her power of molecular combustion into fireworks and flowers. When Piper was feeling insecure about her pregnancy, Wyatt managed to summon Grams and made her corporeal. And when he sensed the trouble in the lack of understanding each other with his parents, he used his powers to switch Piper and Leo's personas; Leo has to feel the trouble of being pregnant and Piper has to feel the trouble of being a Whitelighter.
He was able to conjure a dragon while watching a show about them on TV, which got him and the Charmed Ones in trouble with the Cleaners. The Halliwell Sisters managed to clean everything up and forced the Cleaners to give Wyatt back. Wyatt is destined to wield the powerful sword Excalibur, but Piper wants to keep her son away from the sword for as long as possible, until he's at least 18 years old. Wyatt was once untrustworthy of the new Whitelighter Chris, who happened to be his younger brother from the future. Chris had many times protected Wyatt from evil, even from Gideon the Elder who was out to 'eliminate' Wyatt.
When Wyatt was feeling neglected, he started orbing his baby brother Chris, all over the place, and had created a demon in the form of Leo. Leo and Piper managed to talk to him and gave him words of encouragement to get rid of Evil Leo. Wyatt had used his healing powers to save Piper from a deadly coma, which scared him; he also saw his father getting stabbed. To protect them, Wyatt shrunk his parents and sent them into a miniature doll house. His parents were later returned to normal size by Paige and Phoebe. After the Charmed Ones had faked their own deaths, Wyatt and Chris were to be left in the care of their grandfather, Victor Bennet and disguised themselves to other people besides their own family members.
The future 25-year old version of Wyatt was once summoned to the past (our present) by his mother and Aunt Paige to better understand why he has an imaginary friend. It turned out that the imaginary friend was actually a demon that managed to turn him evil temporarily. He was eventually turned back to good by the comforting words of his father. In the series finale of entitled Forever Charmed, a glimpse into the future shows Wyatt and his younger brother Chris preparing a vanquishing potion together, a sign that they have taken over the fight against evil after the sisters.
Wyatt of the future is now a Whitelighter and has a good relationship with his parents, brother, sister, aunts, uncles and cousins.