I'd say before Ubisoft, Valve was the one to really spearhead DRM by introducing online verification to play Half-Life 2. Before HL2, it was almost unthinkable

I'd say before Ubisoft, Valve was the one to really spearhead DRM by introducing online verification to play Half-Life 2. Before HL2, it was almost unthinkable for a game to require Internet access to be played and most copy protection relied on serial numbers and/or presence of the original game CD. HL2 was high profile enough to make people accept the restriction.