Chariton (KAR-ih-ton), male, and Charis (KAR-iss), female, both mean "grace" in Greek. It is from these that we get the names Carissa and Charisma, and Haris (not to be confused with Harris).
Chariton of Aphrodisias was a 1st century Greek novelist. Saint Chariton the Confessor was a Christian saint native to Iconium.
Charis is a fictional nation in the Safehold series by David Weber. Charis is a metalmark butterfly genus in the species Riodinini. In Greek mythology, a Charis is one of the Charites - goddesses of grace, beauty, charm and feminine warmth. Charis was given to 70 girls in 2016, slowing down a bit in use since its high of 127 girls in 2006. It has been used in the U.S. since 1924.
Charissa and Carissa are much more well known than Charis, and yet they're still pretty uncommon. If you look at the statistics for Carissa, she shoots straight up from 8 girls in 1053 to 1157 girls given the name in 1992, then straight back down to a mere 126 in 2016. Charissa looks a bit the same, except her numbers are much lower. Charissa was given to 25 girls in 2016. The most well known namesake is Charissa from Spencer's The Faerie Queene, where she is a personification of charity. The Carissa spelling doubles as a variant of the Latin name Cara, meaning "dear, beloved."
Charisma, because it is a word, usually doesn't have any trouble with spelling and pronunciation. As a name, actress Charisma Carpenter is perhaps the most famous namesake. Charisma was only used on 59 girls in 2016, and it is still slowly falling in numbers since its high of 196 in the year 2000. Without the h, Carisma is used infrequently and never more than 30 times in a year.