Thomas Stewart Lonsdale (21 September 1882 – 17 March 1973) was a football goalkeeper and centre half.

He played 87 games in his five years at the club, leaving for West Ham United in October 1913 after Grimsby sold him to raise the funds to sign Willis Rippon.

After a shaky start to his West Ham career, he was dropped but later regained his place at the beginning of December.

After he turned up, the board of directors fined him a week's wages, and he was demoted to the reserve team.

[1] He made 31 Second Division appearances in 1923–24, beating off competition from Sidney Brown and Robert Radford.