here's one that evolved from a person
http://en.wikipedia.org/wiki/Helacyton_gartleri
a HeLa cell is a cell which is derived from cervical cancer cells taken from a woman named Henrietta Lacks, who died from the cancer in 1951, and circulated (without Lacks' knowledge or permission) by George Gey. Initially, the cell line was said to be named after a "Helen Lane", in order to preserve Lacks' anonymity. These cells are treated as cancer cells, as they are believed to have stemmed from Ms. Lacks' cervical cancer, but a debate still continues on the classification of these cells.
HeLa are considered "immortal". They do not die of old age and can divide an unlimited number of times as long as basic cell survival conditions are met (i.e. being maintained and sustained in a suitable environment). The current Strain of HeLa cells have been grown in various cell cultures, but all HeLa cells are derived from the same lineage.