Henry James Killilea (June 30, 1863 – January 23, 1929) was an American baseball team owner and attorney.

His parents, Matthew and Mary Killilea emigrated from Ireland in 1849 and established a farm in Winnebago County, Wisconsin.

Killilea was raised on the family farm and attended public school in Winneconne, Wisconsin.

His younger brother, Matthew Killilea, became the president of the Milwaukee Brewers of the Western League, and Henry became a minority owner.

The other members of the group were Connie Mack, Charles Comiskey, and the leader of the effort, Ban Johnson.

Displeased with the decision of the owners, Killilea announced his intention to sell his interest in the club.

However, it was agreed that Somers would continue to hold one share of stock so that he could remain the club's president.

[16] The Boston Post at the time described the Killilea brothers as "capable baseball men" and noted that Henry had "been immensely fortunate and built a big legal practice" and become "one of the wealthiest attorneys" in Milwaukee.

[18] The team won the American League pennant and went on to defeat the Pittsburgh Pirates in the inaugural World Series.

On April 18, 1904, Killilea sold the Boston club to John I. Taylor at a price reported to be $150,000.

After representing the American Association and the Eastern League in litigation seeking higher classifications from the National Commission, the Sporting Life praised Killilea for his "consummate skill and convincing eloquence" and added: Not the least of Mr. Killilea's merits was the fact that he successfully combined aggressiveness with diplomacy; that as author of the present National Agreement he was familiar with his ground at all times; and that he possessed the acquaintance, respect, and confidence of nearly all of the major league magnates.