Sparkler is a unicorn pony.
During Escape from Catrina, she and another pony were painting a banner for Megan's "Welcome Back" party. She became angry at Sundance for accidentally ruining it. Then she was catapulted into the air by Sundance which resulted in her being covered her in paint. She was very rude and unkind at Sundance.
In the UK comics, she collected all kinds of gems and anything glittery.