Blazer

A blazer was a jacket resembling a suit jacket, but cut more casually.

Worn by the Doctor
Many versions of the Doctor wore blazers

The Fourth Doctor wore a rust corduroy blazer during his earlier days. (TV: Robot, The Ark in Space, The Sontaran Experiment, Genesis of the Daleks, Revenge of the Cybermen)

The Tenth Doctor wore pinstripe blazers done on dark brown and light blue, (TV: The Christmas Invasion-The End of Time) or navy and crimson. (TV: Smith and Jones-Dreamland)

Worn by Companions
Amy Pond wore navy blazers with her t-shirts. (TV: Amy's Choice, The Lodger)

Clara Oswald wore a plum purple blazer as part of her undercover suit. (TV: Time Heist)

Peri Brown wore a flaxen blazer with black stripes. (TV: The Mysterious Planet)

Yasmin Khan wore a sage green blazer when she went to Punjab during 1947, (TV: Demons of the Punjab) and a black one when she first meets the Spy Master. (TV: Spyfall)

Ian Chesterton wore a black blazer during a meeting of companions. (TV: The Power of the Doctor)

Worn by the Master
Some versions of the Master wore blazers.

The Master who fought UNIT wore black blazers when posing as businessmen. (TV: Terror of the Autons-The Daemons)

The Bald Master wore velvet blazers done on charcoal (AUDIO: Eyes of the Master) or gunmetal. (AUDIO: Dominion)

The Saxon Master wore black blazers when posing as Harold Saxon. (TV: The Sound of Drums|Last of the Time Lords)

Worn by Others
Henry Van Statten wore a black blazer. (TV: Dalek)

Cathica wore a black blazer as part of her suit. (TV: The Long Game)

Diagoras wore a black pinstripe blazer as did Dalek Sec when he fused with him to become a Human Dalek. (TV: Daleks in Manhattan|Evolution of the Daleks)