Which character in the Harry Potter series is named after the brightest star in the nights sky also called the Dog Star?

The names of the actors who play most of the main roles are:

Daniel Radcliffe - Harry Potter

Rupert Grint - Ron Weasley

Emma Watson - Hermione Granger

Richard Harris - Albus Dumbledore in the 1st and 2nd films

Michael Gambon - Albus Dumbledore in the 3rd onwards (replaced Harris after he died)

Alan Rickman - Severus Snape

Maggie Smith - Minerva McGonagall

Tom Felton - Draco Malfoy

Bonnie Wright - Ginny Weasley

James and Oliver Phelps - Fred and George Weasley

Julie Walters - Molly Weasley

Mark Williams -Arthur Weasley

David Thewlis - Remus Lupin

Ralph Fiennes - Lord Voldemort

Timothy Spall - Peter Pettigrew

Helena Bonham Carter - Bellatrix Lestrange

Gary Oldman - Sirius Black

Matthew Lewis - Neville Longbottom

Evanna Lynch - Luna Lovegood

Rob Coltrane - Rubeus Hagrid