It’s a large Marwari clan from Kolkata, with each branch very very very distantly related to each other. There is the Khaitan & Co law firm branch (officially from Kolkata but now essentially a Mumbai firm), a firm called Khaitan & Partners (Kolkata) and a firm called OP Khaitan (Delhi: owner arrested in August Westland scam). There is also a Khaitan family in Kolkata married into the branch of the Birla family in Kolkata (BK Birla/CK Birla branch) and a Senior Advocate and tax specialist in Kolkata JP Khaitan (who has married a Bengali lady and whose daughter is an academic in one of the world’s most prestigious universities).

All in all, a very useful surname to have!

The first wave of Khaitan's that were dispatched to Delhi from Kolkata, i.e. Late OP Khaitan (erstwhile MP of OP Khaitan & Co; succeeded by Gautam Khaitan) and UK Khaitan (MP of Khaitan & Khaitan; jointly managed with his son Ashutosh Khaitan) now operate their own law firms and are no longer part of the fold. Khaitan & Co is now a father son enterprise of Pintu and Haigreve. Clean and simple. There are other Khaitans like Suman Jyoti Khatan (MP of Suman Khaitan & Co) and Sakate Khaitan (MP of Khaitan Legal Associates). Suman and Sakate were also part of the Khaitan fold in its earlier days. I think both trained under Pintu. Suman has clients like Robert Vadra.

Khaitans migrated from Rajasthan to Bengal and at some point endeared the British to get RB. Their rise was co-terminus with that of the Birlas who had also migrated to Bengal for business purposes. Khaitans continue to be the chief legal counsel for the Birla clan although things have splintered within both the Birlas and Khaitans. Some continued with law, while others went into business and ofc inter-marriages with other business families within the wider Marwari community who made their initial fortunes in Bengal.

Originally aligned with the GOP (as was the Birlas) but once the Left came to power in Bengal, one of the Khaitans (BMK) struck a deep personal and business rapport with Jyoti Basu. That helped them "take over" several British and Scottish businesses (tea, construction, steel etc) when the Red plague swept through Bengal. Same story for the Goenkas.

After JB demise, the Khaitans already beset with internal squabbles and ill-effects of trying to whitewash Union Carbide (India) as Eveready, limped on. Elsewhere the side that went into legal field had also splintered. Despite switching allegiance to TMC, Khaitan businesses continued to bleed. Some connected Marwari business families pitched in but things haven't looked up. Allegations and investigations of funds diversion etc have also cropped up.

One of the Khaitan law firms is embroiled in a high-profile arms deal gone horribly wrong.