Penn was probably the first vampire sired by Angel. Penn and Angel went their separate ways, and did not meet until Penn moved to LA about 200 years later. He was unaware that Angel had a soul, and was most disgusted. After a few battles, Penn was killed by Kate with Angel's help.
Penn thought a lot like a human serial killer, and loved to relive his crimes by repeating them over and over again. His vampire powers were about equal to Angel's, as they were close to the same age.